Treatment of soils with lime and/or hydraulic binders

Transcription

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qê~åëä~íÉ kçîÉãÄÉê OMMU
Technical Guide
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The Technical Department for Transport, Roads and Bridges Engineering and Road Safety (Service d’études
techniques des routes et autoroutes - Sétra) is a technical department within the Ministry of Transport and
Infrastructure. Its field of activities is the road, the transportation and the engineering structures.
The Sétra supports the public owner
The Sétra supplies State agencies and local communities (counties, large cities and urban communities) with
informations, methodologies and tools suited to the specificities of the networks in order to:
• improve the projects quality;
• help with the asset management;
• define, apply and evaluate the public policies;
• guarantee the coherence of the road network and state of the art;
• put forward the public interests, in particular within the framework of European standardization;
• bring an expertise on complex projects.
The Sétra, producer of the state of the art
Within a very large scale, beyond the road and engineering structures, in the field of transport, intermodality,
sustainable development, the Sétra:
• takes into account the needs of project owners and prime contractors, managers and operators;
• fosters the exchanges of experience;
• evaluates technical progress and the scientific results;
• develops knowledge and good practices through technical guides, softwares;
• contributes to the training and information of the technical community.
The Sétra, a work in partnership
• The Sétra associates all the players of the French road community to its action: operational services; research
organizations; Scientific and Technical Network (Réseau Scientifique et Technique de l’Equipement – RST), in
particular the Public Works Regional Engineering Offices (Centres d’études techniques de l’Equipement –
CETE), companies and professional organizations; motorway concessionary operators; other organizations such
as French Rail Network Company (Réseau Ferré de France – RFF) and French Waterways Network (Voies
Navigables de France - VNF); Departments like the department for Ecology and Sustainable Development…
• The Sétra regularly exchanges its experience and projects with its foreign counterparts, through bilateral cooperations, presentations in conferences and congresses, by welcoming delegations, through missions and
expertises in other countries. It takes part in the European standardization commissions and many authorities
and international working groups. The Sétra is an organization for technical approval, as an EOTA member
(European Organisation for Technical Approvals).
Technical guide
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Published by Sétra and carried out by the French Road Engineering Committee (CFTR)
This document is the translation of the work "=Traitement des sols à la chaux
et/ou aux liants hydrauliques ", published in September 2007 under the reference 0718
The CFTR is a federative structure which joins together various components of the French
road community in order to work out an expression of the state of the art shared by all and
used as reference to the road professionals in the fields of pavements, earthworks and road
drainage.
Main actions of the CFTR:
• laying down documents expressing the state of the art;
• drawing up technical advices on fitness for the use of processes, products and
equipments, as well as qualification documents for equipments;
• issuing approvals for road laboratories;
• carrying out procedures of certification and conformity with standards.
French Road Engineering Committee
Association ruled under the law of 1 st july 1901.
Its Head office is located at:
10 rue Washington 75008 Paris
Phone: 33 (0)1 44 13 32 87 – Fax: 33 (0)1 42 25 89 99
mél : [email protected]
internet : http://www.cftr.asso.fr
Treatment of soils with lime
and/or hydraulic binders – Application to the construction of pavement base layers– Technical guide
This guide was drafted by the CFTR (French Road Engineering Committee) sectoral committee on
"methodology" of the by a working group made up of representatives of the Scientific and Technical Network
of the Ministry with responsibility for public works, the technical directorates of firms and local and regional
authorities.
Its content has been validated by a survey conducted among CFTR members.
The working group was led by Jean-Claude Auriol (LCPC Nantes) and Daniel Puiatti (Groupe Lhoist).
Comité de rédaction:
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Joseph ABDO
Georges AUSSEDAT
Jean-Michel BALAY
Jean-Pierre BENABEN
Pierre BENSE
Joël BOSSE
Christian BOUCHENY
Maurice BUFALO
Ludovic CASABIEL
Jean-Hugues
COLOMBEL
Alain Destombes
Alain FEVRE
Daniel Gandille
Honoré Goacolou
Philippe HAUZA
René Hiernaux
Yves Jolivel
Michel KERGOËT
Yves LACOT
François MIERSMAN
Pascal OGER
Daniel PIERRON
Alain QUIBEL
Bernard ROUSSEL
Dominique SEIGNEUR
Jean-Claude VAUTRIN
Jacques VECOVEN
François VERHEE
Yves Vincent
(CIMBÉTON, centre professionnel)
(UNPG)
(LCPC)
(CETE du Sud-Ouest – LRPC Toulouse)
(Entreprise SCREG)
(Entreprise Eurovia)
(DREIF - LROP)
(Entreprise Valérian)
(CIMBÉTON, centre professionnel)
(CETE Normandie-Centre - LRPC Rouen)
(DREIF - LROP)
(CETE Normandie-Centre - LRPC Rouen)
(Entreprise GUINTOLI)
(Entreprise EUROVIA)
(Entreprise COLAS)
(CETE Nord-Picardie – LRPC Saint-Quentin)
(Conseil Général de Seine-Maritime)
(DREIF- LREP)
(Entreprise CE&RF)
(Société SURSCHISTE)
(Société RINCENT BTP)
(CETE de l’Est - Lrpc Nancy)
(CETE Normandie-Centre - CER Rouen)
(CETE Normandie-Centre - LRPC Blois)
(CETE de l’Est - LRPC Nancy) h (Deceased-)
(Sétra)
(Entreprise HOLCIM)
(USIRF)
(Entreprise EUROVIA)
– 4 –
Translate November 2008
Contents
1 - Introduction ............................................................................................... 7
2 - St udies .................................................................................................... 10
2 . 1 - T h e t yp e s o f s o i l c o ve r e d b y t h e g u ide .................................................. 10
2 . 2 - T h e p r o g r e s s i ve n ature of studies ......................................................... 11
2 . 3 - Char ac t eriz at i o n of the deposit ............................................................. 12
2.3.1 -
Minimum features of the geotechnical survey .................................................................................. 12
2.3.2 -
Evaluation of the uniformity of the deposit....................................................................................... 12
2.3.3 -
The mechanical strength criterion of the granular fraction ............................................................. 14
2 . 4 - M i x d e s ign studies ................................................................................ 15
2.4.1 -
Objectives of the mix design study.................................................................................................... 15
2.4.2 -
Need for pretreatment with lime ....................................................................................................... 15
2.4.3 -
Choice of binder for the mix design study ........................................................................................ 15
2.4.4 -
Soil specimen used for the study ....................................................................................................... 15
2.4.5 -
Complete study ................................................................................................................................. 16
2.4.6 -
Limited study .................................................................................................................................... 17
2.4.7 -
Identification of the constituents....................................................................................................... 17
2.4.8 -
Reference tests for compaction ......................................................................................................... 17
2.4.9 -
Study of the immediate stability ........................................................................................................ 17
2.4.10 -
Specimens ......................................................................................................................................... 18
2.4.11 -
Conservation..................................................................................................................................... 20
2.4.12 -
Performance ..................................................................................................................................... 21
2.4.13 -
Sensitivity study of mechanical performance.................................................................................... 21
3 - D e s ign ..................................................................................................... 22
3 . 1 - T r a f f ic data ........................................................................................... 23
3.1.1 -
The Ti traffic classes......................................................................................................................... 23
3.1.2 -
The TCi cumulative traffic classes.................................................................................................... 23
3.1.3 -
Aggressiveness of traffic ................................................................................................................... 24
3 . 2 - C la s s e s o f subgrade ............................................................................. 25
3.3 - Design parame ters ................................................................................ 25
3.3.1 -
Materials........................................................................................................................................... 25
3.3.2 -
The interface conditions ................................................................................................................... 29
3 . 4 - Pa ve m e n t design .................................................................................. 29
3.4.1 -
Application ....................................................................................................................................... 29
3.4.2 -
Minimum qualities ............................................................................................................................ 29
3.4.3 -
Types of structures............................................................................................................................ 30
3.4.4 -
Surfacing layers................................................................................................................................ 30
3.4.5 -
Constructional measures .................................................................................................................. 30
3 . 5 - Ver i f ic a t io n o f frost design ................................................................... 31
3 . 6 - Exa mp l e s of design .............................................................................. 31
3.6.1 -
First example (Table 26) .................................................................................................................. 31
3.6.2 -
Second example (Table 27)............................................................................................................... 35
4 - Implementation ........................................................................................ 38
4.1 - Forew ord .............................................................................................. 38
4 . 2 - Pre p a r a t i o n of materials ....................................................................... 39
– 5 –
4.2.1 -
Sorting of the material ...................................................................................................................... 39
4.2.2 -
Removing aggregate above a certain size ........................................................................................ 39
4.2.3 -
Pretreatment with lime ..................................................................................................................... 39
4.2.4 -
Creation of stockpiles and rehandling.............................................................................................. 40
4.2.5 -
Moistening ........................................................................................................................................ 40
4.2.6 -
Validity of the selected methods........................................................................................................ 42
4.3 - Manufacture ......................................................................................... 42
4.3.1 -
The level of quality of the treatment equipment for pavement base layers ....................................... 43
4.3.2 -
Treatment in situ............................................................................................................................... 47
4.3.3 -
Treatment in a plant ......................................................................................................................... 48
4 . 4 - T r a n s p o r t and la ying ............................................................................. 49
4.4.1 -
Transport of mixtures ....................................................................................................................... 49
4.4.2 -
Laying ............................................................................................................................................... 49
4.5 - Su rface protection .............................................. E r r eur ! Sig ne t n on dé f in i .
4.6 - Su rface protection ................................................................................ 51
4.6.1 -
Characteristics related to the nature of the treated soils.................................................................. 51
4.6.2 -
Mechanical stresses .......................................................................................................................... 51
4.6.3 -
Climatic stresses ............................................................................................................................... 51
4.6.4 -
The different types of surface protection .......................................................................................... 52
4.6.5 -
Choice of the type of surface protection ........................................................................................... 53
4 . 7 - Q u a l it y control ..................................................................................... 56
5 - A b b r e v i a t i o n s - s ymbols - definitions ....................................................... 65
6 - B i b l iography ............................................................................................ 68
7 - A nnexes ................................................................................................... 75
7.1 - Annex A ............................................................................................... 75
7.2 - Annex B ............................................................................................... 76
Specifications for soils used in pavement base layers......................................................................................... 76
Economic factors................................................................................................................................................. 77
7.3 - Annex C ............................................................................................... 78
The contribution of each item to the cost of the treated soil in question............................................................. 78
The contribution of each piece of machinery to the cost of the treated soil in question ..................................... 78
7.4 - Annex D ............................................................................................... 79
– 6 –
Introduction
The technique of soil treatment has been known about and used for many centuries – some Roman roads still
bear witness to the fact – but it has developed considerably since the 1960s. Of the countries that have applied
the technique, France is one of those that has made the greatest progress as a result of successive mastery of the
treatment of embankment materials, capping layers and then pavements. This progress is due to the combined
efforts of all the protagonists: awarding entities, contract managers, contractors, equipment and binder
manufacturers who have attempted to make the best possible use of treated soils by the rational characterization
of their properties and improving procedures, materials and products. Table 1 provides a schematic summary of
this process. It shows the presence of mutual influences very clearly, and, in particular, shows how an
prescriptive document, which is the logical outcome of any progress, can itself initiate a new phase of
development.
Thus, the publication in 1981 of the "Manuel de conception des chaussées neuves à faible trafic" by the Sétra
and the LCPC [2], and the many ensuing regional structural catalogues [8], [9], [10], [11], [12], [13], [14], [15]
marked the start of the use of fine treated soils in pavement base layers. This application has come into
widespread use since, particularly in regions where there is a shortage of aggregate that meets the applicable
specifications. Solid experience has been acquired thanks to the commitment of the entire profession which was
convinced that the technique would provide an economical response to the key question of the optimized use of
natural resources, which is a major concern with regard to “Sustainable Development”.
In order for the development of this application to continue under the best possible conditions, the stakeholders
involved in road construction felt that it was necessary to summarize their experience in this guide. The guide
places particular emphasis on the importance of preliminary studies, project design and the conduct of works for
obtaining structures which perform well. It also sets out to reduce the risks caused by the lack of uniformity of
natural materials by detailing the specific measures and know-how that supplement the normal rules of good
practice for conventional techniques.
The guide draws on our knowledge about the different phases of implementing the technique, which has
incidentally already been published in the documents and standards to which it refers. It is essentially a
supplement to these documents and can be thought of as a continuation of the technical guide "Traitement des
sols à la chaux et/ou aux liants hydrauliques" published by the Sétra and the LCPC (GTS) [4] in January 2000
whose structure therefore becomes:
• Part A: General concepts
• Part B: The treatment of soils in embankments
• Part C: The treatment of soils in capping layers
• Part D (this guide): The treatment of soils in pavement base layers
However, in contrast to the GTS, the soil categories that are considered have been deliberately restricted, to
exclude materials for which:
• existing references or experience are too partial or inclusive to be applied;
• no reference to an application is known.
Initially, therefore, the guide covers only certain natural soils.
This is why it takes the form of a methodological guide which will be modified with reference to local
application documents, for example in the form of regional guides some of which exist already (see
Bibliography).
– 7 –
In order to ensure that the technical approach is comparable with that used for conventional aggregate-based
materials (unbound graded aggregate (GNT), graded aggregate bound with a hydraulic binder (GTLH), road
base asphalt (GB), etc.), the following approach has been applied:
• After the collection of the available information and documents on the subject, analysis focused in particular
on information from construction sites, starting with soil studies and the design of soil treatment and ending
with the appraisal of the long-term performance of pavements under traffic.
• This work revealed the need to modify each phase of a project (soil study – mix design study – design –
construction - tests) with reference to:
– the nature, variability and prior knowledge of the soil which is a candidate for treatment;
– the planned application (sub-base layer and/or road base layer);
– the type and scale of future stresses;
– the accepted risks with reference to the nature of the works.
For example, it should be borne in mind that a car park for light vehicles does not need to withstand anything
like the same level of stress as a road that carries through traffic.
• Particular attention has been given to preliminary studies and the fact that the possibility of using a soil
depends on knowledge of the results of the studies on the soil in question and a minimum amount of local
experience.
• Last, the limits and potential for the use of treated soils in pavement base layers have been identified based on:
– the existence or lack of representative applications;
– monitoring of the performance of pavements that makes it possible to make a judgment about their
durability and long-term behaviour.
The characteristics to be considered for structural design have been established on the basis of all aspects of the
above approach.
It should be mentioned that the publication of this guide coincides with the completion of an important phase of
European standardization on this topic. This involves, in particular, the standards in the series NF EN 14227,
parts 10 [71], 11 [72], 12 [73], 13 [74] and 14 [75], which lay down specifications for soils treated with lime and
hydraulic binders (the precise references are given in the bibliography). Fully consistent with these standards, it
describes how the studies are to be performed, the structural design parameters, and the manufacturing and
laying conditions for the materials. Thus, following the recommendations in this guide correctly will necessarily
facilitate application of the standards in question.
– 8 –
Date
Development of equipment
Development of products
1965
Agricultural
equipment
Limes and
cements
Development of codification
Stages
Specific mixer with a rear rotor
Non speed-related volumetric
spreader
1985
1995
New generation mixer
Mixer with a central rotor
High power mixer
Speed-related volumetric spreader
Variable width weighing spreader
Sprinkler plough
Mixing plant
Limes and cements
Appearance of hydraulic road
binders
Development of hydraulic road
binders
Low dust binders
Recommandation sur le
traitement à la chaux
Sétra-LCPC 1972
Recommandation pour la réalisation
des Terrassements Routiers (RTR)
Sétra-LCPC-1976) (SETRA-LCPC
Recommendations for Road
Earthworks 1976)
Guide Réalisation des
Terrassements Routiers
(GTR) Sétra-LCPCpremière édition 1992 [5]-
Guide Traitement des Sols à la
chaux et liants hydrauliques pour
remblais et couches de forme
(GTS)-Sétra-LCPC-2000 [4]
Manuel de conception des
chaussées neuves à faible trafic
SétraLCPC1981 [2]
NF P 98-115 Exécution des
corps de chaussées [33]
NF P 98-114-3 Méthodologie
d’étude des sols traités utilisés en
assises [32]
Knowledge of performance
Rationalization of procedures
(SETRA-LCPC
Recommendations for treatment
with lime 1972).
Occasional
use
1975
Start of mix design
Control of procedures
Development
Applications
Optimization of design
Single combined capping layer and roadbase – Pavement base layers
Capping layer
Embankments
Table 1: The development and control of soil treatment in France
– 9 –
1 - Studies
1.1 - The types of soil covered by the guide
The soil categories, as defined in the standard NF P 11-300 [16], covered by this guide are as follows,
without considering whether they are homogeneous or not:
• fine soils with more than 35 % passing a 80 μm screen. When used in pavement base layers, a particle size
and clay content limit is applied. Therefore, only A1 and A2 soils will be considered in this guide;
sandy soils (D ≤ 6.3 mm) with less than 35% passing an 80 μm screen and a high clay content
(VBS > 0.2). These can be used on local roads. They correspond to soil types B2, B5 and B6. In the case of
use in pavement base layers, a limit must be applied for the maximum clay content: due to a lack of
experience, the maximum VBS is to be limited to 1 for B2 soils and 2.5 for B6 soils depending on the fines
content of the sand. Only B5 soils and some B2 and B6 soils will therefore be considered in this guide;
• gravelly soils (D > 6.3 mm) with less than 35% passing an 80µm screen and VBS > 0.1. These correspond
to category Bi soils. In the case of use in a pavement base layer, a limit is applied for the maximum particle
size and clay content. Only soils B3, B5 and some B4 and B6 soils will be considered in this guide.
•
Thus, the two principal criteria that limit the use of soils in pavement base layers are the maximum particle
size and clay content. On this basis, the soils which are covered in this guide are summarized in Table 2.
Types of soil covered by this
guide after preparation if
required
Fine soils
Sandy soils
Gravelly soils
Limiting criteria
Clay content
A1, A2
VBS < 5
or Ip < 20
B5, B6
VBS < 2.5
B2
0.2 < VBS < 1
B5, B6
VBS < 2.5
B3, B4
0.1 < VBS < 1
Particle size in mm
Dmax (*)
D (**)
≤ 31.5
≤ 20
≤8
≤ 6.3
≤ 31.5
≤ 20
(*) Dmax: maximum size of the largest particles in the soil (according to NF P 11-300) [16 ]
(**) D: maximum size of screen for which the passing fraction is between 80% and 99%
Table 2: clay content and particle size criteria for the soils that can be used in pavement base layers
The clay content criterion used to characterize soils is either the VBS or the IP (NF P 94-051) [22]. The VBS
(NF P 94-068) [24] or the methylene blue value of a soil differs from the MB (NF EN 933-9) [60] used in the
aggregate norm XP P 18-545 [76]. They measure the same property under conditions which are specific to
each material and express it differently. An approximate correspondence of the following type between these
two measurements can be accepted:
VBS = 0,1 x (MB) x (2 mm passing fraction)/ 100
Most of the soils covered by the standard NF P 11-300 [16 ] will require preparation to achieve the minimum
level of uniformity specified in the sections below for levels H1 or H2. This preparation may be carried out
at the site where the soil is extracted by various stockpiling, screening or mixing operations. The guide
therefore requires the deposit to be assessed in order to characterize the uniformity of the soil in situ and
decide whether it is necessary to perform preparation operations to make it uniform. The uniformity
classification of the soil described in section 2.3.2 therefore relates to its final state before treatment for use
in a pavement base layer.
– 10 –
1.2 - The progressive nature of studies
In order to avoid impasses (technical, economic, timetabling, etc.), the greatest attention must be paid to
insuring that appropriate knowledge is obtained at each stage of the project.
Table 3 shows the factors which are usually considered in order to decide on the content of a soil treatment
study.
Content of study
Gathering the available documentary data (geological maps,
geotechnical and meteorological data sheets, design documents
from similar works, etc.).
Stage of project
normally involved
Expected outcome
Technical possibility of considering the use of the
treated soil in pavement base layers.
Collection of local expertise, particularly with regard to the possible
presence of inhibitors in the soil. In the absence of successful local
experience, evaluation of the suitability of the soil for treatment by
means of accelerated swelling tests as specified in the standard
NF EN 13286-49 [68] supplemented by indirect tensile strength
tests according to the standard NF EN 13286-42 [65] on another
series of specimens prepared and conditioned in accordance to the
standard NF EN 13286-49 [68].
Preliminary study
Analysis and summary of this information with a view to the soil
treatment for the pavement base layer works in question.
General characterization of the deposit intended for the pavement
base layer on the basis of the information from the general
geological and geotechnical survey of the route.
Confirmation that the soil in the deposit intended for
the pavement base layer is suitable for treatment.
If necessary, a number of additional samples should be taken
(using an auger or a shovel, for example) for more detailed
characterization of the deposit.
- of the volumes of usable soils;
All this data should be summarized.
Assessment:
- of the construction techniques and equipment
required;
Draft design
- of the most suitable product (s) and the quantities
that will probably be necessary in order to carry out a
preliminary design for the solution covering technical
and economic aspects and the construction time
frame.
Finalization of the characterization of the deposit, production of
The drawing up of rules for the proportions to be used
representative specimens and performance of a full mix design
as a function of the nature and state of the soils and
study in order to specify the proportioning with reference to the
the targeted level of mechanical performance.
target performance and, if relevant, the anticipated states of
Design (*)
Characterization and localization of deposits.
humidity (a variable proportion of these mix design studies may be
Information about the most technically appropriate
postponed until the construction design phase that takes place
construction equipment and methods.
during the works, response times permitting).
(*) The conduct of the “Design” stage studies takes between 3 months to 1 year depending on the prior level
of knowledge of the soil and the regional use of this soil in pavement base layers.
Table 3: Content of studies and anticipated outcomes as a function of the stage of the project.
It is indispensable for this study procedure to be applied in full in the case of works where there are major
technical and economic stakes and for which a soil treatment solution is considered in the tender invitation
documents (DCE).
In the case where the contract allows for alternatives, the DCE must specify that the contractor must provide
details about the characterization of the deposit and the mix design study as specified in the Design stage in
Table 3 to support its tender.
– 11 –
1.3 - Characterization of the deposit
The deposit to be categorized may consist of:
• a deposit of natural soil in situ, in the case of a material to be extracted from a road cut or from a borrow
pit. This is the case which is dealt with in the rest of this document.
• a stockpile of material which is described in a Soil Data Sheet (FTS, see annex A) or a similar document
drawn up on the basis of identification tests conducted as the stockpile was created (a minimum of one test
per 500 m³). In this case, assessment of the uniformity of the stockpile is made by applying the same
criteria as for the first case.
• a stockpile of material which has not been the subject of an identification test during its creation. This
stockpile cannot be used as it stands. It is however possible to return to the previous situation by moving
the stockpile and reconstituting a stockpile of identified material.
The batches of uniform soil that are ready for use are then identified using a Soil Data Sheet (annexes A and
B). This distinguishes 2 levels of soil uniformity, H1 and H2. Level H3 describes the limits to use.
1.3.1 -
Minimum features of the geotechnical survey
On the basis of the test borings and visual observation of the removed materials, it is possible to make a
preliminary classification on the basis of geological groups of materials which are visually similar.
Each of these groups is then characterized by a minimum number of geotechnical identification tests which
depends on the volume of material to be used.
In the absence of other instructions, this minimum number can be evaluated using Table 4.
(V) volume of the
pavement layer to
be constructed
(m³)
Minimum number of tests to characterize each group of soils
Nature of soil
State of humidity
V 104
9
16
V > 104
9 V / 104
16 V / 104
Table 4: minimum number of tests to characterize the soil groups
1.3.2 - Evaluation of the uniformity of the deposit
The uniformity of the geological groups of soils is then evaluated as follows:
• in the case of fine soils (A1, A2):
the identification of these soils systematically involves characterization tests to measure their clay content,
in principle VBS for A1 soils and Ip (or VBS) for A2 soils.
The material’s clay content is considered to be uniform if the relative range (er) of the VBS or Ip
measurements is ≤ 40 %. If this is not the case, it must be decided (at this stage of the study) if it would be
possible by applying (realistic) special measures –sorting for example – to determine which subgroups of
the soils in the deposit exhibit the desired uniformity.
Once the deposit has been divided up in this way, if it is necessary, “Standard Proctor” tests according to
the standard NF P 94-093 [25] or “non-modified Proctor tests” according to the standard NF EN 13286-2
[64], are to be conducted on extreme samples of these groups or subgroups and a judgment is made about
the uniformity of the material as shown in Table 5.
– 12 –
Level of
uniformity
Relative
range of the
ρd NPO (er)
(*)
H1
er ≤ 4 %
H2
4 < er ≤ 6 %
H3
er > 6 %
Relative range
of the VBS or
Ip
measurements
(er) (*)
Possible use in pavement base layers
Sub-base layer with traffic ≤ T1
er < 40%
Road base layer with traffic ≤ T3
Sub-base layer with traffic ≤ T2
er < 40%
Road base layer with traffic ≤ T4
Not usable in pavement base layer
er < 40%
(*) er is the ratio between the range of the measurements and their average.
Table 5: classification and use of class A1 and A2 treated fine soils according to their level of uniformity
• Sandy or gravelly soils class B2, B3, B4, B5, B6:
for these soils, which contain a granular fraction and clayey fines, identification of the samples necessarily
involves VBS tests and grading tests (fraction passing an 80 µm screen, fraction passing a 2 mm screen,
Dmax) conducted on samples taken during the surveys.
• If the Dmax of the materials of the samples is incompatible with use in a pavement layer (Dmax > 31.5 mm),
the particle size of the samples is limited to 31.5 mm (it is necessary to decide whether limiting the particle
size in this way is feasible at the construction site).
The results of the VBS and grading tests conducted on the samples prior to this screening are then
recalculated in order to characterize the screened material.
An initial analysis of the uniformity of the results is then conducted in order to decide whether sorting,
preparation or division of the deposit into zones which are easily identifiable during works is necessary.
A decision is then made about the uniformity of the deposit or the zones that have been created on the basis
of Table 6.
– 13 –
Uniformity criteria
Level of
uniformity
Possible uses in pavement
base layers
Fraction passing an
80 μm screen
er** de VBS (1)
mean
e*
≤ 15 %
≤6%
Base for traffic ≤ T3
> 15 %
≤8%
Sub-base layer pour traffic ≤
T2
≤ 15 %
≤8%
Sub-base layer for traffic ≤ T1
≤ 40 %
H1
H2
≤ 40 %
and
and
Base for traffic ≤ T4
H3
Not usable in pavement base
layers
> 40 %
and
> 15 %
≤ 12 %
≤ 15 %
>8%
> 15 %
> 12 %
e* of fraction
passing a
2mm
screen***
and
≤ 20 %
and
≤ 30 %
or
> 30 %
* e is the range of measurements
** er is the ratio between the range of the measurements and their average.
*** only in the case of gravelly soils or medium or coarse sandy soils
(1)
only applies when VBS is equal to or less than 0.2 er
Table 6: classification and use of treated sandy or gravelly soils according to their uniformity
1.3.3 - The mechanical strength criterion of the granular fraction
The mechanical strength of the materials is determined:
• in the case of sandy soils, by the friability of sands (Fs) measured according to the standard NF P 18-576
[18];
• for gravelly soils, by the Los Angeles (LA) value measured according to the standard NF EN 1097-2 [62],
and the Micro Deval (MDE) value measured according to the standard NF EN 1097-1 [61].
The scope of application of these materials will then be decided on the basis of Table 7.
Type of soil
Sandy soils
Pavement layer
Sub-base layer
Traffic class
< or = T4
T3
T2
T1
Fs < 50
Fs < 50
Base
Gravelly soils
Sub-base layer
E
E
Base
E
D
E
D
Table 7: intrinsic characteristics (XP P 18-545) [76]
– 14 –
1.4 - Mix design studies
1.4.1 - Objectives of the mix design study
The study must fix the proportion of hydraulic binder, the proportion of lime when pretreatment is necessary,
the bulk density and the compaction moisture content required for the works. It also gives the mechanical
characteristics used for design, the water content of the mix and estimates its frost resistance. If previous
studies have not revealed the sensitivity of the performance of the mix to dispersion in the mix design
parameters, this analysis should be conducted in the course of the mix design study.
The methodological standard that is applicable for the soils covered by this guide is NF P 98-114-3 [32].
Two types of study are defined by the standard NF P 98-114-3 [32]: the full study and the limited study
which is used for mixes that are well tried and tested. Nevertheless, above traffic level ≥ T3, a full study
must be performed for tried and tested mixes if experience is insufficient to predict their performance with
this level of traffic.
1.4.2 - Need for pretreatment with lime
When soil treatment is applied to the capping layer, but even more when it is applied to pavement base layers
for which a higher level of performance is required, the role of lime is not limited to controlling the hydric
condition of the soil to be treated. The regulation phase, which is extremely important, should already have
been performed during the creation of stockpiles of uniform usable materials.
The function required of lime in this document is to prepare the clayey soil to form a stable mixture with a
hydraulic binder. To do this, the attempt is made to achieve an optimal level of flocculation of the clayey
colloids, which makes the soil change from a compact state (stacking of flakes of clay) to a well-spaced or
flocculated state (disordered arrangement), which is much more compatible with the uniformity required of
the mix. The attempt is therefore made above all to achieve the most intimate mixture possible between the
clayey soil and the lime and not simply to coat soil aggregates, even if the fineness of the soil before
pretreatment appears visually satisfactory (with agglomerates < 20 mm).
The pretreatment of low plasticity soils is also necessary, unless a laboratory study has shown otherwise.
However, it is frequently advisable to specify an optimum content that should not be exceeded at the risk of
limiting, or even impairing, the mechanical performance.
1.4.3 - Choice of binder for the mix design study
Generally, the mix design study should be conducted by the contract manager during the project design
stage. As it is quite often not possible to know what binder the contractor will use to perform the works, it is
recommended to choose a standardized cement from a local cement plant. As a rule, the binder consists of a
CEM II A or B 32.5 binder as described in the standard NF EN 197-1 [57]. The choice of a hydraulic road
binder for this study is therefore only justified if there is a considerable amount of experience of its use with
the soil in question and it is in frequent use locally. The studies performed with the cement or the selected
hydraulic road binder provides a means of verifying that the mechanical class used in the design calculation
is obtainable. Moreover, this design mechanical class will be used later in order to evaluate alternatives
proposed by the contractors, in accordance with Part 25 of the General Technical Specifications (CCTG) [1].
1.4.4 - Soil specimen used for the study
The mix design study is to be conducted on a specimen of soil or a mixture of soils which are representative
of the deposit(s) that are being considered (see section 2.3), that have been identified and whose uniformity
is known.
– 15 –
This sample should be subjected to testing to establish its suitability for treatment using the accelerated
swelling tests as specified in the standard NF EN 13286-49 [68] supplemented by indirect tensile strength
tests as described in the standard NF EN 13286-42 [65] conducted on another series of specimens that have
been manufactured and conserved in accordance with the standard NF EN 13286-49 [68]. This test should
take place at the earliest possible stage in the project in order to identify any risks of swelling or setting
failure. It is desirable to perform it during the preliminary studies or the draft design stage adopting the
approach described in Table 3 in Section 2.2. The results are to be interpreted on the basis of the criteria set
out in Table 8.
Rit (MPa) after 7days
conservation in water
Volumetric swelling Gv (%)
(NF EN 13286-49) [68]
Suitable
Doubtful
Unsuitable
Gv < 5
(NF EN 13286-42) [65]
and
5 ≤ Gv ≤ 10
or
Gv > 10
or
Rit > 0.2
0.1 ≤ Rit ≤ 0.2
Rit < 0.1
Table 8: criteria for interpreting suitability for treatment
When the verdict of the test is “suitable”, the study must nevertheless be continued. When the results are
considered to be “doubtful”, the continuation of the study depends on the construction site context (the
treatment study may be continued if there is some hope of bringing about an improvement by increasing the
spread rate, selecting other binders or pretreatment of the soil). In the case where treatment is “unsuitable”,
the studied solution will be abandoned.
1.4.5 - Complete study
The study methodology is described in the standard NF P 98-114-3 [32].
The complete study, which is required for all mixtures for which experience is limited, includes:
• identification of the studied soil sample and, if applicable, the other constituents;
• identification of the binders, lime and activators;
• study of the compacting references using the modified Proctor test according to the standard NF EN
13286-2 [64] or the standard Proctor test according to the standard NF P 94-093 [25];
• study of the immediate stability by determining the on-site bearing ratio (IPI) according to the standard NF
EN 13286-47 [67];
• determining the age at which construction site traffic is permitted;
• measuring the workability time according to the standard NF EN 13286-45 [66] (Studies are currently in
progress to specify a suitable test procedure for fine soils);
• evaluation of the water resistance and frost resistance;
• study of long-term mechanical performance;
• study of the effect of dispersion in composition on mechanical performance;
• determination of the basic mix design.
Data about lime pretreatment operations: if construction site conditions (see § 4.2.3) give the impression
that the proportion of lime will have to be changed, it is essential to perform, in addition to the mix design
study, a study of sensitivity to the proportion of lime that includes minimum and maximum limits for
pretreatment. In this case, the study may be conducted using the method described in the standard NF P 98114-3 [32] or in Table 14 in this guide.
– 16 –
1.4.6 - Limited study
The limited study, which is only performed in the case of mixes that have already been tested (as defined in
the standard NF P 98-114-3 [32], omits the determination of the age at which construction site traffic is
permitted, the workability time and frost resistance. As the tests are only performed on one mix design, it is
not possible to modify the proportions in order to specify a different basic formula.
Although the standard does not require determination of the water sensitivity, doing so is recommended
during the limited studies: it is frequently the only criterion that indicates whether preliminary treatment with
lime is required, particularly in the case of A1, B5 and B6 soils.
1.4.7 - Identification of the constituents
Soils
The sample that is used, which is in conformity with the FTS of the soil batch which it represents (see § 2.3
and annex A), should be identified, in particular on the basis of its origin and its classification according to
NF P 11-300 [16] and by any other necessary test (for example, chemical or mineralogical analysis).
Binders and limes
These are identified and verified according to the applicable standards (NF EN 459-1 [58] and NF EN
14227-11 [72] for limes, NF EN 197-1 [57] for cements and NF P 15-108 [17], awaiting publication of the
European standard NF EN 13282 [63] that is currently being prepared, , for hydraulic road binders) or on the
basis of the CFTR technical assessments or similar documents.
1.4.8 - Reference tests for compaction
The reference standards are NF EN 13286-2 [64] for the modified Proctor test and NF P 94-093 [25] for the
standard Proctor test.
Depending on the type of soil study, the following compaction energy will be applied:
• The modified Proctor energy for sands with less than 35% of particles smaller than 80µm. In the case of
some sands, it is difficult to achieve the modified Proctor density on site (lamination, insufficient
cohesion). If construction site data are available, the conditions under which specimens are prepared in the
laboratory may be adjusted;
• the standard Proctor energy for most other soils. It is however possible to use the modified Proctor test for
some gravelly soils with a low clay content, on condition that experience has shown that the dry density
which is normally achieved during works with these treated soils is compatible with this test.
1.4.9 - Study of the immediate stability
The determination of the on-site bearing ratio (IPI) is conducted as described in NF EN 13286-47. The
bearing capacity thresholds given in Table 9 apply to treated materials with the water content in the study
formula.
Type of soil
Minimum on-site bearing
ratio (IPI)
A1, A2
20
B sandy
30
B gravelly
50
Table 9: minimum values of the on-site bearing ratio (IPI) for treated materials
– 17 –
1.4.10 - Specimens
Preparation of mixtures
This is performed according to the standard NF P 98-230-3 [43].
The dimensions of specimens
The dimensions of the specimens are selected on the basis of the D of the studied soil or mixture of studied
soils. The correspondence is given in Table 10. The dimensions given in bold in the table are to be preferred
(over the dimensions given in normal italic characters).
Type of soil
A1, A2
D(1) ≤ 6.3 mm
Ø5
×
h 5 cm (**)
Ø5
×
Ø5
× h 10 cm (**)
Ø5
× h 10 cm (**)
h 5 cm (**)
Ø 10 × h 10 cm
Ø 10 × h 10 cm
Ø 10 × h 20 cm
Ø 10 × h 20 cm
Ø 16 × h 16 cm
B gravelly
B sandy
6.3 mm < D ≤ 20 mm
Ø 16 × h 32 cm
Ø5
×
h 5 cm (**)
Ø5
× h 10 cm (**)
Ø 10 × h 10 cm
Ø 10 × h 20 cm
Ø 16 × h 16 cm
Ø 16 × h 32 cm
(1) D is the maximum screen size for which the passing fraction is between 80 % and 99 %
(see Table 2 in chapter 2).
(*) tests conducted on the 0-6 mm fraction.
(**) only for the measurement of Rt
Table 10: specimen dimensions
The Ø 16 x h 16 cm, Ø 16 × h 32 cm and Ø 10 x h 20 cm specimens are prepared according to the standard
NF EN 13286-52 [69] or NF EN 13286-53 [70], the Ø 5 × h 5 cm or Ø 5 × h 10 cm or Ø 10 × h 10 cm
specimens, according to the standard NF EN 13286-53 [70], even if the dimensions given in Table 10 are not
all mentioned in these standards.
The specimen preparation procedure
In order to take account of the difficulties of compaction that occur in thick layers, two cases are considered.
Case 1: a layer with a thickness ≤ 30 cm. In order to be consistent with the standards relating to
methodologies for studying treated gravels and sands for pavement base layers, specimens for unconfined
compression tests or tensile tests (direct or by diametral compression) are compacted to a dry density of
98.5% of ρde at the OPN or 97 % of ρde at the OPM depending on the studied soil (see § 2.4.7). Table 11
shows the specimen preparation procedure to be followed.
– 18 –
Case 2: a layer with a thickness > 30 cm or a single combined capping layer and roadbase. The
specimens for the unconfined compression tests are compacted to a dry density of 98.5% of ρde at the OPN
or 97 % of ρde at the OPM depending on the studied soil. Tensile tests (direct or by diametral compression)
performed on specimens that have been compacted to a dry density of 96% of the OPN or 95% of the OPM
depending on the studied soil. Table 12 shows the specimen preparation procedure to be followed.
Type of test
Type of soil
A1 and A2
B sandy (see Table 2 + §
2.4.7)
B gravelly (see Table 2 + §
2.4.7)
B gravelly (low clay content,
whose behaviour is known,
see Table 2 + § 2.4.7)
Slenderness
ratio
Unconfined compressive
strength
2
Indirect tensile strength
and modulus
1
strength
2
and modulus
1
Direct tensile strength
and modulus
2
strength
2
and modulus
1
and modulus
2
strength
2
and modulus
1
and modulus
2
Design dry density (ρde) and
design moisture content (we)
ρde = 98,5 % of the OPN
we = OPN
Mode of
compaction
double action static
vibrocompression
ρde = 97 % of the OPM
we = OPM
Double action static
or
vibrocompression
vibrocompression
we = OPN
we = OPM
or
vibrocompression
or
vibrocompression
Table 11: the specimen preparation process depending on the soil and type of test
Layers of thickness ≤ 30 cm
– 19 –
Type of soil
A1 et A2
B sandy (see Table 2 + §
2.4.7)
B gravelly (see Table 2 + §
2.4.7)
B gravelly (low clay content,
whose behaviour is known,
see Table 2 + § 2.4.7)
Type of test
Slenderness
ratio
strength
2
and modulus
1
strength
2
and modulus
1
and modulus
2
strength
2
and modulus
1
and modulus
2
strength
2
and modulus
1
and modulus
2
Design dry density (ρde) and
design moisture content (we)
Mode of
compaction
we = OPN
ρde = 96 % of the OPN
we = OPN
we = OPM
we = OPM
or
vibrocompression
vibrocompression
we = OPN
ρde = 96 % of the OPN
or
vibrocompression
we = OPN
we = OPM
or
vibrocompression
we = OPM
Table 12: specimen manufacture process depending on the soil and type of test.
Layers of thickness > 30 cm or a single combined capping layer and roadbase
1.4.11 - Conservation
The specimen conservation procedure is as follows:
• the temperature of conservation should be 20°C ± 2°C;
• the specimens are to be conserved in their moulds in a moist atmosphere with a relative humidity equal to
or greater than 90%, or in their moulds in a closed waterproof plastic bag.
– 20 –
1.4.12 - Performance
The performance to be achieved after treatment is displayed in Table 13.
Criteria
Thresholds
Age at which construction site traffic is
permitted
Rc at the age of the treated soil when it is open
to traffic depending on the aggressiveness of
the traffic (see Table 34)
Water sensitivity
Ratio: Rc (28j + 32 i )/ Rc 60 j
Frost resistance
Rit at the age of the soil at the probable first
occurrence of frost
Rc ≥ 1.0 MPa (*) for aggressiveness of level A (***)
Rc ≥ 1.2 MPa (*) for aggressiveness of level B (***)
Rc ≥ 1.5 MPa (*) for aggressiveness of level C (***)
≥ 0.80 if VBS ≤ 0.5
≥ 0.70 if VBS > 0.5
> 0.25 MPa
Classification according to
Long term performance
Rt or Rit and E after at least 90 days (**)
NF EN 14227-10 [71]
or NF P EN 14227-13 [74 ]
(*) The temperature of conservation is normally 20°C. However, if the works are to take place towards the end of the year, the average local temperature may
be used. The 1.2 MPa threshold may be raised in certain cases.
(**) And also perhaps after 28 and/or 60 days, in particular in order to evaluate frost resistance.
(***) See Table 34
Table 13:mechanical performance of treated soils
1.4.13 - Sensitivity study of mechanical performance
This study is based on:
• measurement of the direct or indirect tensile strength,
• measurement of the secant moduli at 30% of the failure load.
The tested specimens are generally 90 days old. This duration of curing can be increased (for example up to
180 days) for some slow-setting binders.
Usually, the study is performed as specified in NF P 98-114-3 [32] , under the conditions set out in Table 14.
0.8 le
le
1.2 le
0.9 we
95 % ρde
we
X
1.1 we
0.9 we
ρde
we
X
X
X
X
X
1.1 we
0.9 we
102 % ρde
we
X
1.1 we
Where ρde , we and le are the density, bulk density, the water content and the binder
content of the studied formula..
Table 14: conditions to be applied to investigate the effect of variations in proportioning
– 21 –
If the deposit or the mixture of soils which is intended for use exhibits variations in water content which
exceed the extremes considered in Table 14 above, the water content ranges may be extended on the basis of
local experience, on condition that the bearing capacity and the density objectives are achieved during the
works.
The results obtained are to be entered in the design chart of the standard NF P 98-114-3 [32]. Exploitation of
these results in accordance with the standards using linear interpolation, makes it possible to specify the
basic mix design for the intended performance class. If no result achieves the intended class, a new study
must be performed. The proportioning of the new study formula may be defined by extrapolating the results
of the sensitivity study.
2 - Design
Treated soil structures are to be designed using the technical guide “Conception et le dimensionnement des
structures de chaussées” Sétra-LCPC 1994 [3] (referred to below as the 1994 Technical Guide for the Design
of Pavement Structures). This method consists of comparing the tensile stress (σt) at the base of the layer of
treated soil, calculated using the Burmister model, to the allowable stress of the material (σad), calculated
using the formulae below.
σad = σ6 . ( NE /106 )b . kc . kd . kr . ks
kr= 10-ubδ and δ= ( (SN2 + (Sh.c/b)2 )1/2
where:
• σ6 is the stress for which the tensile failure of a 360 day old specimen is obtained after 106 cycles (MPa);
• NE is the number of equivalent standard axle loads for the PL traffic;
• b is the fatigue slope of the material expressed as a bi-logarithmic equation;
• kc is a calibration coefficient;
• kd is a coefficient that takes account of the discontinuities in rigid structures, taken as 1 for the structures
covered by this guide;
• kr is a coefficient which adjusts the allowable deformation or stress value with reference to the design risk
and the dispersion factors;
• ks is a coefficient that takes account of local variations in the bearing capacity of the underlying unbound
layer;
• SN is the standard deviation of the logarithm of the number of cycles that results in fatigue failure;
• Sh is the standard deviation of the thickness in the layer of laid materials (m);
• c is a coefficient that links the variation in deformation to the random variation in pavement thickness
(cm–1);
• u is a random variable of the reduced centred normal distribution for the risk r (the values of u with
reference to the design risk rc are provided in the checklist in the annex of the 1994 Technical Guide for the
Design of Pavement Structures [3]);
• rc is the design risk.
N.B. As the materials covered by this document are highly sensitive to water, particular care must be paid to
pavement design in order to avoid water ingress and ponding (see § 3.4.5).
The design hypotheses to be applied are those given in the 1994 Technical Guide for the Design of Pavement
Structures, subject to the conditions stated below.
– 22 –
2.1 - Traffic data
These data differ from those in the 1994 Technical Guide for the Design of Pavement Structures [3] because
the definition of PL in the standard NF P98-082 [28] has changed to include any vehicle with a total weight
of 3.5 tonnes or over (gross vehicle weight ≥ 35 kN).
Two classifications will be considered in order to evaluate the traffic carried by a road:
• The Ti traffic class which corresponds to the total number of PLs with a total gross weight equal to or
over 35 kN, per day and for each traffic direction when the road is opened to traffic;
• this classification is used in order to choose the geometrical characteristics of the road and the pavement
materials;
• The TCi traffic class which corresponds to the cumulative number of PLs for each direction on the most
highly trafficked lane that the pavement is expected to carry during its design life;
this classification is used to design pavements.
2.1.1 -
The Ti traffic classes
Table 15 sets out the Ti traffic classes on opening of the road, as a function of the average annual daily
traffic (AADT) for PLs on the most highly trafficked lane.
PLs with a total gross
weight ≥ 35 kN, for each 0
direction (ADT) on opening
of the road
Ti traffic class on opening of
the road
25
trafficT5
50
trafficT4
150
trafficT3
300
trafficT2
750
trafficT1
2000
trafficT0
Table 15: Ti traffic classes on opening of the road
2.1.2 - The TCi cumulative traffic classes
For pavement design, it is necessary to evaluate the total number of PLs the road will have to withstand
during its service life.
The following formula is used to compute cumulative traffic (TC):
t x d x (d - 1) ⎤
⎡
TC = 365 x N x ⎢d +
⎥⎦ x r
2
⎣
This equation considers a linear increase in traffic.
N is the number of PLs with a total gross weight ≥ 35 kN per day and for each direction on opening of the
road
t is the annual linear rate of the increase in traffic
d is the service life (in years)
r is the coefficient that represents the transverse distribution of PLs on the carriageway
– two-way roads with a width ≥ 6 m :
r=1
– two-way roads with a width of 5 to 6 m:
r = 1.5
– two-way roads with a width < 5 m:
r=2
– 23 –
– one-way roads:
r=1
– 2 x 2 lane roads:
r = 0.9
– 2 x 3 lane roads:
r = 0.8
In general, for the roads where these techniques are applied, the service life can be considered to be 20 years
with a traffic growth rate of 0.02 per year.
Table 16 shows, under these conditions, the cumulative traffic classes (TCi) that have been selected, for twoway roads with a width of more than 6 metres carrying different Ti traffic classes on opening.
Ti traffic class on opening
traffic T5
traffic T4 traffic T3 traffic T2 traffic T1
Cumulative traffic class TCi TC0 (1) (2)
TC1
TC2
TC3
TC4
TC5 (3)
Limiting value of cumulative
traffic of vehicles with a total
gross weight ≥ 35 kN
105
to
2 105
2 105
to
5 105
5 105
to
1.5 106
1.5 106
to
2.5 106
2.5 106
to
6.5 106
104
to
105
(1) Class TC0 has been added for the purposes of this document in order to make it possible to take account of very low traffic roads
(2) For cumulative traffic levels of less than 104 PLs, the structures will be designed for 104 PLs
(3) For cumulative traffic above class TC5, the use of treated soils in pavement base layers is not permitted.
Table 16: Cumulative traffic classes TCi for a service life of 20 years and a traffic growth rate of 0.02 per year
2.1.3 - Aggressiveness of traffic
The type of PL may vary greatly from one pavement to another.
In order to take account of these differences, a coefficient of average aggressiveness (CAM) is determined on
the basis of the distribution spectrum of the PLs using the pavement.
This coefficient can be used to calculate the number of equivalent standard axles (NE) using the formula NE
= TCi.CAM.
When the type of PL traffic is known, the CAM is calculated using the method described in the 1994
Technical Guide for the Design of Pavement Structures [3].
For roads where precise data on the distribution of the types of PL is lacking, the CAM values shown in
Table 17 will be used for treated soils.
Ti Traffic class on opening of
the road
traffic T5
traffic T4 traffic T3 traffic T2 traffic T1
Equivalent cumulative traffic
class Ci(1)
TC0 - TC1
TC2
TC3
TC4
TC5
CAA
0.4
0.5
0.7
0.8
0.8
(1) With the hypothesis of a 20 year design life and an annual rate of traffic increase of 0.02
Table 17: traffic aggressiveness coefficients
– 24 –
2.2 - Classes of subgrade
Pavement construction usually involves adding materials to a subgrade after acceptance.
For the design of treated soil pavement layers, the minimum long-term bearing capacity classes, which vary
depending on the traffic, are as follows:
• Ti traffic < T3 traffic: subgrade bearing capacity ≥ PF1
• Ti traffic ≥ T3 traffic: subgrade bearing capacity ≥ PF2
N.B.
The 1998 Sétra LCPC catalogue of standard new pavement types [7], which applies to the national road
network specifies a minimum subgrade of PF2.
In the case of PF1 subgrades, the bearing capacity of the subgrade when the pavement layers are constructed
must be equal to or greater than 35 MPa in order to permit adequate compaction of the treated layer.
In the case when the use of in-situ treated soils in pavement layers still does not permit acceptance of the
pavement subgrade, it is necessary to estimate the bearing capacity of the subgrade on the basis of the
geotechnical characteristics of the materials or to measure the bearing capacity at the top of the layer to be
treated before any treatment operation.
2.3 - Design parameters
2.3.1 - Materials
Section 2.1 defines two types of soil on the basis of the identification of the initial material:
• fine or sandy soils,
• gravelly soils.
During treatment design, a material quality class (SOIL Ti) is defined on the basis of the pair of values E - Rt
as defined in the standards NF EN14227-10 [71] or NF EN14227-13 [74].
As design is performed on the basis of characteristics after 360 days and the values of Rt and the moduli are
frequently obtained after 90 days or 180 days, in the absence of specific results, the values measured at a
minimum age of 90 days are to be applied without correction.
For information only, the values of the E – Rt value pairs obtained during the studies that have been
performed have been plotted on the graph in the standard that defines the quality class of treated soils (see
Table 18 and Graph 1).
– 25 –
Type of material
Rt in MPa after 90 days
E in MPa
1
Silt from Rouen
0.53
2600
2
Silt from Rouen
0.61
3100
3
Silt from Rouen
0.55
5600
4
Silt from Rouen
0.43
4530
5
Silt from Rouen
0.97 (360 j)
5640
6
Silt from Rouen
0.36
4010
7
Silt from Rouen
0.86 (360 j)
4070
8
Clay from Autun
0.17
2200
9
Silt from Lille
0.90
6100
10
Silt from Lille
1.09 (360 j)
7360
11
Granitic Sand from St-Brieuc
0.73
7400
12
Granitic Sand from St-Brieuc
1.03 (360 j)
6890
13
Silt from A1 St-Quentin
0.25
3100
14
0.26
2650
15
0.37
3400
16
0.28
4500
17
Silt from A1A2 St-Quentin
0.41
3800
18
Silt from A1A2 St-Quentin
0.47
4100
19
Silt from A2 IdF
0.24
1650
20
Silt from A2 IdF
0.32
3374
21
Silt from A2 Lille
0.30
4000
22
Silt from A2 Lille
0.34
4500
23
Silt from A2 Lille
0.34
3000
24
Silt from A2 Lille
0.26
2700
25
Sand from St-Quentin
0.57
10350
26
B2 gravel from St-Quentin
0.26
3500
27
B5/B6 gravel from St-Quentin
0.36
5500
28
B5/B6 gravel from St-Quentin
0.34
4650
Table 18:the study results plotted on the graph
– 26 –
- each plot shows the trend for the soil in question
- SOIL T1 and SOIL T2 are the categories that are the most frequently used for fine or sandy soils
Graph 1: results of studies for treated fine or sandy soils and gravelly soils
Résistance en traction Rt (MPa) à 90 jours minimum: Tensile strength Rt –MPa after a minimum of 90 days
• Module élastique E (103 MPa) à 90 jours minimum: Elasticity modulus E (103 MPa ) after a minimum of
90 days
• Sols fins et sableux: Fine sandy soils
• Sols graveleux: Gravelly soils
• Droite sols fins et sableux: Line for fine sandy soils
• Droite sols graveleux: Line for gravelly soils
The threshold values in Table 19 have been used for the examples given in Section 3.6. They may also be
used in order to create an initial design for a catalogue of regional structures.
Type of soil
Fine sandy soils
Gravelly soils
Boundary between
Boundary between
Boundary between
SOIL T0 / SOIL T1
SOIL T1 / SOIL T2
SOIL T2 / SOIL T3
E = 2500 MPa
E = 4000 MPa
E = 6200 MPa
Rt = 0.20 MPa (1)
Rt = 0.44 MPa
Rt = 0.8 MPa
E = 3300 MPa
E = 8200 MPa
E = 16200 MPa
Rt = 0.24 MPa
Rt = 0.54 MPa
Rt = 1.02 MPa
(1)The value Rt = 0.20 MPa corresponds to the minimum required to obtain a non frost susceptible material (Rit ≥ 0.25 MPa)
Table 19: thresholds derived from graph 1
– 27 –
Taking account of manufacture
The value of E and Rt that are obtained for specimens in the laboratory are reduced in a way that reflects the
differences between the performance obtained in the laboratory and on site.
Two levels of quality of treatment are considered for this purpose:
• treatment quality AC1;
• treatment quality AC2.
The two levels of quality AC1 and AC2 are defined in the section on Implementation (see § 4.3.1.).
Treatment in a plant is only a possibility if it is guaranteed that the materials will flow correctly through the
different units in the plant (class B soils and class A soils that have been pretreated with lime).
Table 20 gives the reductions to be applied to the moduli E and strengths Rt measured in laboratory as a
function of the quality of the treatment.
Quality of treatment
AC1
AC2
E
25 %
35 %
Rt
25 %
35 %
Parameter
Table 20: reductions of the modulus E and the strength Rt as a function of the quality -level AC
The transition from Rt to σ6 used for design is obtained by using the equation σ6 = 0.95 Rt.
Other design parameters
On the basis of fatigue studies (see Bulletins de liaison des laboratoires des Ponts et Chaussées n° 133 [77]
and 134 [78]) leads to the adoption of the following values for treated soils:
• slope of the fatigue line 1/b
1/b = - 11
• standard deviation of the fatigue law SN
Fine soils
SN = 0.8
Sandy soils
SN = 0.8
Gravelly soils
SN = 1.0
These values are identical to those stated in the 1994 Technical Guide for the Design of Pavement Structures
[3].
• Standard deviation of thicknesses Sh
Sh depends on the type of treatment and the type of material. Table 21 gives the values to be applied.
Type of treatment
Imported materials (1)
Materials treated in-situ
0.025 m
0.04 m
Type of material
Fine or sandy soils
Gravelly soils
0.03 m
0.05 m
(1) values obtained from the 1994 Technical Guide for the Design of Pavement Structures
Table 21: standard deviation of thicknesses
– 28 –
• Calibration coefficient kc
kc = 1.4
• Risk value rc
Table 22 sets out the risk values rc to be applied in the calculations.
Risk value rc
Cumulative traffic class Tci
TC1 and TC0
TC2
TC3
TC4
TC5
Semi-rigid structures
20 %
12.5 %
10 %
7,5 %
5%
Foundations
Composite structures
50 %
50 %
35 %
20 %
10 %
Table 22: risk values rc
• Other coefficients
The other coefficients that are involved in design are identical to those defined in the 1994 Technical Guide
for the Design of Pavement Structures [3].
2.3.2 - The interface conditions
The interface conditions to be considered are listed in Table 23.
Type of interface
Nature of the interface
Treated soil sub-base on a subformation or subgrade
bonded
Treated soil road base layer on a treated soil sub-base
semi- bonded
Road base layer made from graded aggregate bound with a hydraulic binder on a treated soil
sub-base
semi- bonded
Composite structure
1st phase road base asphalt on a treated soil sub-base
semi- bonded
2nd phase road base asphalt on a treated soil sub-base
debonded
Asphalt concrete or road base asphalt on a layer of treated soil
Table 23: interface conditions
semi- bonded
Il all cases, particular attention must be paid to protecting the surface of the treated soil and promoting
bonding with the overlying layer (see § 4.5)
2.4 - Pavement design
2.4.1 - Application
The treated soils covered by this guide may be used in road base layers for traffic up to level T3 and in subbase layers for traffic up to level T1.
2.4.2 - Minimum qualities
The minimum quality class for treated soils depends on the envisaged use (road base layer or sub-base layer)
and the traffic the pavement carries.
The minimum necessary quality classes are set out in Table 24.
Traffic class Ti
trafficT5
trafficT4
trafficT3
trafficT2
trafficT1
Road base layer
SOIL T2
SOIL T2 (*) or SOIL T3
SOIL T3
(**)
(**)
Sub-base layer
SOIL T1
SOIL T1
SOIL T2
SOIL T2
SOIL T3
(*)A class of SOIL T2 may be accepted only for sandy and gravelly soils.
(**) Use in a road base layer for T2 or T1 traffic may be envisaged in the context
of a project that trials techniques that improve the quality of the interface between pavement base layers and the surfacing.
– 29 –
Table 24: minimum quality classes
2.4.3 - Types of structures
When the treated materials are used in sub-base layers, different types of road base layers can be considered
resulting in the following types of structures:
• composite structures;
• semi-rigid structures with a road base layer consisting of imported materials bound with hydraulic. The
case where treated soils are imported for use in a road base layer can be assimilated to this type of
structure;
• other semi-rigid structures with a thick asphaltic road base layer but which cannot be classified as a
composite structure;
• inverted structures with a layer of unbound graded aggregate covered with bituminous materials;
• cement concrete structures. In this case, it is necessary to lay a first layer of asphalt concrete in the case of
high traffic levels, followed by a cement concrete wearing course.
2.4.4 - Surfacing layers
1st case: treated soil used in a road base layer
Table 25 gives the total thickness of the asphalt layers to be laid on top of the layers of treated soil.
Cumulative traffic TCi
Traffic TC0
Traffic TC1
Traffic TC2
Traffic TC3
Fine soils
6 cm
6 cm
10 cm
12 cm
Sandy soils
Surface
dressing
6 cm
8 cm
10 cm
Gravelly soils
Surface
dressing
Surface dressing
8 cm
10 cm
Type of soil
In the case of use in car parks and similar areas, a 6 cm asphalt concrete
surfacing layer is necessary in all cases even in the absence of PLs.
Table 25: thickness of the surfacing
In all cases, the mix design of the asphaltic layer must provide a maximum amount of waterproofing
(flexible asphalt concrete).
2nd case: treated soil used in a sub-base layer
The usual rules for designing surfacing layers as a function of the type of road base layer used are applicable.
2.4.5 - Constructional measures
As the materials covered by this guide are very sensitive to water, particularly care must be paid to
pavement design in order to avoid the ingress and stagnation of water.
All or some of the following measures may be considered:
• constructing the layer of treated soil 0.5m wider than usual, and waterproofing it if necessary;
• draining stormwater away as rapidly as possible into ditches and outlets, increasing the transverse slopes of
verges and waterproofing them if necessary;
• construction of draining edge screens to remove internal water as rapidly as possible, particularly in areas
with wet climates.
– 30 –
2.5 - Verification of frost design
The verification of frost design is to be performed as stipulated in the 1994 Technical Guide for the Design
of Pavement Structures [3].
This method may be simplified by not considering mechanical protection and by using the simplified method
for calculating the thermal protection provided by the pavement structure.
In accordance with this guide, any pavement with a value of Rit ≥ 0.25 MPa is considered not to be frost
susceptible.
2.6 - Examples of design
Design has been performed for two structures:
• the first is a structure using treated fine or sandy soil, on a PF2 subgrade;
• the second is a fine or sandy in-situ treated soil on a PF1 subgrade consisting of the existing soil.
2.6.1 - First example (Table 26)
The first design is for a semi-rigid structure made from fine or sandy treated soil of quality AC1 laid on a
PF2 subgrade.
Three materials, corresponding respectively to the classes SOIL T3, SOIL T2, and an intermediate class
corresponding to the hypotheses for treated soil in the catalogue of structures for Ile de France (the Greater
Paris Region).
The mechanical performance design values that are applied for these materials are as follows:
SOIL T3
E ≥ 6200 MPa
Rt ≥ 0,80 MPa
SOIL T2
E ≥ 4000 MPa
Rt ≥ 0,44 MPa
Treated IdF soil
E ≥ 5333 MPa
Rt ≥ 0,56 MPa
Treatment quality AC1
This leads to the following design parameters:
SOIL T3
E = 6200 MPa x 0.75 = 4650 MPa
σ6 = 0.80 x 0.75 x 0.95 = 0.57 MPa
SOIL T2
E = 4000 MPa x 0.75 = 3000 MPa
σ6 = 0.44 x 0.75 x 0.95 = 0.31 MPa
Treated IdF soil
E = 5333 MPa x 0.75 = 4000 MPa
σ6 = 0.56 x 0.75 x 0.95 = 0.40 MPa
These mechanical performance hypotheses are at the bottom of the class for SOIL T3 and SOIL T2 classes
and in the middle of the class for IDF treated soil.
Other hypotheses:
• Slope of the fatigue line
1/b = − 11
• Standard deviation of fatigue
SN = 0.8
• Standard deviation of thickness
Sh= 0.025
• Calibration coefficient
kc = 1.4
• Risk
see § 3.3.1.2, Table 22
• Interface hypotheses:
– bonded sub-base layer on subgrade
– semi-bonded road base layer on a treated soil sub-base
– 31 –
– semi-bonded asphaltic material on a road base layer.
• Cumulative traffic used for structural design:
– traffic TC0
– traffic TC1
– traffic TC2
– traffic TC3
– 32 –
Cumulative traffic
class over a period of
20 years TCi
SOIL T3
and number of
equivalent standard
axles NE used for
design
12 cm
SOIL T2
Treated IDF soil
Not used
as a road base layer
Not used
as a road base layer
B
traffic TC3
28 cm
NE = 0.6 106 Eq
10 cm
B
10 cm
BB
BB
10 cm
traffic TC2
43 cm
26 cm
NE = 0.2
106
Eq
6 cm
B
6 cm
In 2
layers
BB
30 cm
BB
6 cm
traffic TC1
26 cm
42 cm
NE = 0.1 106 Eq
6 cm
6 cm
traffic TC0
B
In 2
layers
30 cm
BB
BB
6 cm
35 cm
NE =0.05 106 Eq
28 cm
25 cm
Table 26: example of quality AC1 imported treated soil laid on a PF2 subgrade
To provide an illustration, the calculation is given in detail for the following configuration:
• traffic class TC2 (cumulative traffic of 0.2.106 equivalent standard axles – Eq);
• a class PF2 subgrade;
• a treated soil of class SOIL T3.
– 33 –
For a SOIL T3, with the parameters described above, the allowable stress at the base of the treated soil is
obtained with the following equation:
b
⎛ NE ⎞
σad = σ 6 x ⎜ 6 ⎟ x kc x kd x kr x ks
⎝ 10 ⎠
where:
•
•
•
•
•
•
•
σ6
NE
b
kc
kd
kr
ks
= 0.57 MPa
= 0.2 106
= - 1/11
= 1.4
=1
= 10-ubδ
= 1/1.1
with a 12.5% risk (traffic TC2), u = – 1.150
$Note du traducteur: il faut remplacer « soit » par « or » entre les équations.
and δ =
cSH 2 ⎤
⎡ 2
⎢SN + ( b ) ⎥ soit δ =
⎣
⎦
0,02 x 2,5 2 ⎤
⎡ 2
⎢0,8 + ( - 1/11 ) ⎥ = 0,9708
⎣
⎦
which gives kr = 0.792
from which:
σad = 0.57 x (
1
0,210 6 − 1 / 11
= 0,664 MPa
)
x 1,4 x 1 x 0,792 x
6
1,1
10
Modelling the structure using the Alizé design software [79].
10 cm
ASPHALT CONCRETE
E = 5400 MPa
semi-bonded interface
26 cm
treated soil
E = 4650 MPa
bonded interface
PF2 E = 50 MPa
– 34 –
This modelling leads to the stresses and strains set out in matrix 1.
Hypotheses
Layer
Sliding
hypothesis
Bonded
hypothesis
Semi-bonded
hypothesis
εt
Base of asphalt
concrete
- 130.7
-1
- 65.85
σt
Base of the layer
of treated soil (MPa)
- 0.792
- 0.514
- 0.653
εz
Base of the layer
of treated soil
450.9
271.5
361.2
Matrix 1: deformation stresses calculated using the Alizé software [79]
The structure with 26 cm of class SOIL T3 treated soil and the semi-bonded hypothesis leads to a σt of 0.653
MPa, which is slightly below the allowable value of 0.664 MPa.
The εt values of the asphaltic materials and the εz values at the surface of the subgrade are also well
validated.
2.6.2 - Second example (Table 27)
This is a semi-rigid structure consisting of in-situ treated fine or sandy soils of quality AC2. The in-situ soil
(prior to treatment) provides a subgrade with a bearing capacity of PF1.
Three materials have been selected corresponding to the classes SOIL T3, SOIL T2, and an intermediate
class exhibiting the hypotheses adopted for treated soil in the catalogue of structures for Ile de France (the
Greater Paris Region).
The mechanical performance design values that are applied for these materials are as follows:
SOIL T3
E ≥ 6200 MPa
Rt ≥ 0.80 MPa
SOIL T2
E ≥ 4000 MPa
Rt ≥ 0.44 MPa
Treated IdF soil
E ≥ 4615 MPa
Rt ≥ 0.49 MPa
Treatment quality AC2
This leads to the following design parameters:
SOIL T3
E = 6200 MPa x 0.65 = 4030 MPa
σ6 = 0.80 x 0.65 x 0.95 = 0.49 MPa
SOIL T2
E = 4000 MPa x 0.65 = 2600 MPa
σ6 = 0.44 x 0.65 x 0.95 = 0.27 MPa
Treated Idf soil
E = 4615 MPa x 0.65 = 3000 MPa
σ6 = 0.49 x 0.65 x 0.95 = 0.27 MPa
– 35 –
These mechanical performance hypotheses are at the bottom of the class for SOIL T3 and SOIL T2 classes
and in the bottom third of class SOIL T2 the IDF treated soil.
Other hypotheses:
• Slope of the fatigue line
1/b = − 11
• Standard deviation of fatigue
SN = 0.8
• Standard deviation of thickness
SH = 0.04
• Calibration coefficient
kc = 1,4
• Risk
see § 3.3.1.2, Table 22
– bonded sub-base layer on subgrade
– semi-bonded road base layer on a treated soil sub-base
– semi-bonded asphaltic material on a road base layer.
• Cumulative traffic used for structural design:
– traffic TC0
– traffic TC1
– traffic TC2
– traffic TC3
– 36 –
Cumulative traffic
class over a period of
20 years TCi
SOIL T3
SOIL T2
Treated soil from IDF
Not selected for
Road base layers
Not selected for
Road base layers
and number of
equivalent standard
axles NE used for
design
12 cm
B
traffic TC3
37 cm
NE = 0,6
106
Eq
10 cm
B
10 cm
BB
BB
10 cm
traffic TC2
48 cm
35 cm
NE = 0,2 106 Eq
6 cm
B
6 cm
In 2
layers
BB
In 2
45 cm
layers
BB
6 cm
traffic TC1
34 cm
47 cm
NE = 0,1 106 Eq
6 cm
traffic TC0
BB
6 cm
layers
In 2
44 cm
layers
BB
BB
6 cm
45 cm
NE =0,05 106 Eq
In 2
33 cm
In 2
layers
In 2
42 cm
layers
Table 27: example of structures with quality AC2 treated soil In-situ treated soil on a PF1 subgrade
– 37 –
3 - Implementation
3.1 - Foreword
The widespread use of treated soils in capping layers has resulted in gradual technological improvements
which mean that the use of this type of material can be envisaged in pavement base layers. The use of treated
soils in pavement base layers is therefore primarily the application of an “earthworks” technique (even if
nowadays the boundary between the capping layer and the sub-base layer is sometimes very unclear).
There are therefore major differences between the manufacturing and laying “chain” for works involving
treated soil for use in a pavement base layer and for conventional works for pavement layers, for example
with regard to the following points:
• the uniformity of the “raw” material is variable;
• this material may have been pretreated with lime, a varying length of time before use;
• the material generally retains a degree of water sensitivity;
• unlike with granular material, there is not always a stockpile;
• manufacturing usually takes place by mixing in-situ and more rarely in a plant. Consequently, the water
content and particle size distribution are more difficult to control.
The success of a treated soil pavement base layer will consequently depend to a very great extent on the
quality of the operations which transform the raw material deposit into the completed treated soil layer.
The fundamental points to which the participants in such works must pay attention include:
• the material must have uniform grading and moisture content and a Dmax value of less than 31.5mm;
• the binder(s) must be added in the correct amounts regularly and taking into account of the fact that
manufacturing and laying will give results that differ from the laboratory performance study;
• the mix design should enable the works to be conducted under normal climatic conditions in spite of the
material’s residual sensitivity;
• compliance with the laying thickness and degree of compaction specified by the studies must be obtained;
• the interfaces must provide the best possible bonding between the layers.
Finally, the techniques used provide must allow the above result to be achieved in the case of both smallscale and large-scale works.
The sections which follow take stock of the rules that have been developed on the basis of various operations
involving different materials: sands with moderate clayey contents, low plasticity silts, granitic sands, etc.
The end of the section on laying contains a general flow chart of soil treatments for pavement base layers
(Figure 1) which summarizes the various stages that are required for the scenarios considered in this guide
(treatment in situ, in a plant, etc.).
However, the experience that has been acquired cannot be considered as definitive; a range of variations may
be encountered during these works and before any operation is performed analysis of all the potentially
influential parameters must be conducted.
An economic study has been performed (see annex C) in order to see how each item contributes to the total
cost of a treated soil used in pavement base layers. This analysis has revealed that the cost of design and
testing are marginal compared with the total cost of treatment.
– 38 –
3.2 - Preparation of materials
The preparation of the materials prior to treatment with hydraulic binders aims to transform the soil into a
“semi-industrial” product with regular characteristics and uniformity that meets the requirements set out in
the section on Design (see § 2 .3 .2).
In what follows a number of soil preparation techniques which may help achieve the quality required for
pavement base layers are described.
3.2.1 - Sorting of the material
The aim of this is to remove any undesirable materials that are mixed with the deposit of soil to be treated. It
is performed applying the techniques which are normally used in earthworks and makes intermediate
stockpiling necessary.
3.2.2 - Removing aggregate above a certain size
As has already been mentioned in the section on Design, the Dmax of the treated soils used in road
foundations must comply with the values set out in Table 2 in the section on Design (see § 2 .1).
To achieve this, one or more of the following may be necessary, depending on the nature of the soils to be
treated:
• pretreatment of clayey materials with lime;
• soil loosening using a plough in order to bring blocks to the surface where they are grouped together,
collected and, if necessary, crushed;
• in-situ size reduction using special machinery; if in-situ size reduction requires several passages of
machinery, intermediate compaction between each passage will improve the effectiveness of the operation;
• screening the materials;
• etc.
3.2.3 - Pretreatment with lime
This operation may be performed, as necessary:
• at the cutting site (for example, in the case of rubbly soils which require preliminary screening…),
• at a temporary stockpile (for example, in the case of soils which require additional homogenization, in the
case of in-plant treatment, in the case of environmentally sensitive works, when there is a shortage space
for extraction or laying…),
• during laying (for example, in the case of imported homogeneous soils or aggregate …).
The proportion of lime (a minimum of 1%) must be that decided on during the treatment study. If the soil has
a high moisture content, the proportions may be changed on the basis of the hydric condition, unless this has
been rejected by the study. If the meteorological conditions (heat, drought) mean that it is necessary to add
water, an alternative solution may be envisaged, for example the use of slaked lime, which uses less water, or
milk of lime, which, in contrast, provides a slight degree of moistening if required. The most common
solution is to moisten the soil more before the treatment operations in order to take account of the drying of
the soil caused by the lime. Failure to comply with the proportions of lime which are recommended by the
study is likely to lead to variations in:
• Proctor reference density;
• mechanical performance.
A speed-related spreader should be used, with a precision e ≤ 5 % and Cv < 10.
– 39 –
Mixing must be performed with a horizontal shaft soil pulverizer. It should be borne in mind that the speed
of travel of this equipment can have a direct impact on the fineness which is obtained. The finest possible
result should be sought, at most 0/20 mm.
In all cases, closure of the treated surface by compaction as the work progresses is indispensable.
After pretreatment with lime, it is necessary to wait for at least 12 hours before treatment with hydraulic
binders.
3.2.4 - Creation of stockpiles and rehandling
The creation of a stockpile or temporary depot can help to improve the uniformity of a soil if appropriate
construction methods and equipment are used.
The methods that are usually used to create stockpiles of materials are applicable to the creation of
provisional stockpiles of soils:
• preparing storage areas and creating slopes or ditches at the base of the future slopes to permit drainage of
water from the stockpile thus avoiding the build-up of water within it;
• laying an anti-contamination geotextile at the base of a stockpile if necessary;
• building up the stockpile in single layers whose thickness will depend on the nature of the materials and
equipment used;
• creating slopes with sufficient gradients with levelling, if necessary, and light compaction in order to
guarantee the stability of the stockpile and limit water ingress;
• careful shaping of the slopes;
• creating berms which can be used by construction site traffic if necessary;
• in the case of granular soils which are prone to segregation, the materials should be dumped on the layer
which is in the process of being laid and spread using a bulldozer as work progresses;
• materials should be rehandled using a method which is compatible with the way in which the stockpile has
been built up. If the stockpile has been created in thin layers (< 0.60 m) rehandling is best performed from
the front (loader, shovel) but if the stockpile consists of continuous heaps dumped by tipcarts and trucks in
large thicknesses, rehandling in thin layers should be preferred (scraper);
• when rehandling stops, it is advisable to leave a small thickness of material to avoid contamination
between the underlying soil and the stockpiled materials .
When performed in this way, rehandling of the stored materials helps to improve their uniformity with regard
to particle size distribution and water content.
The stockpiling and rehandling operations may also be used to moisten the materials.
The uniformity provided by these operations is measured in the same way as the uniformity of a deposit.
3.2.5 - Moistening
The aim of this is to give the soil a water content that means that after treatment with a hydraulic binder the
mixture achieves the water content which has been specified by the mix design study, to within 1%. The
operation must take account of the water content of the soils and the losses which may occur during
treatment (evaporation, addition of dry materials). The free water in the soil must be uniformly distributed
within the soil agglomerates and immediately around them, which means a soak time which will depend on
the clay content of the soil is required.
If the water content needs to be corrected by less than 1%, this may be done immediately before the binder is
spread or during mixing.
If a correction of more than 1% is required, pre-moistening should performed in one or more stages.
Depending on the nature of the soils, the minimum time intervals between two moistening/mixing sequences
are set out in Table 28:
– 40 –
– 41 –
Soil
Time limit
A1,A2
4 hours
B5, B6
2 hours
B2,B4
30 minutes
B3
0
Table 28: minimum time interval between two moistening/mixing sequences
Each moistening operation, which is limited to 2%, must be performed on material that has been scarified to
a depth of at least two-thirds of the thickness of the layer in order to limit the accumulation or flow of water
on the surface. Each moistening operation must be followed by mixing throughout its thickness.
The quantity of water added must be controlled, which means that it is necessary to use:
• pumps whose flow is coupled to the vehicle’s travel speed;
• flow meters;
• systems which provide good cross-sectional regularity (water spray bars, nozzles, plough systems).
Sprinklers with a fishtail sprinkler are prohibited.
The quality of the water must meet the requirements set out in NF P 98-100 / type 1 (or possibly type 2 after
verification by a specific study).
3.2.6 - Validity of the selected methods
All soil preparation procedures must undergo validation tests to show that the uniformity objectives specified
in the section on Studies (see § 2.3.2), as a function of the type of layer and the forecast anticipated traffic,
will be achieved.
3.3 - Manufacture
The technological progress made by equipment manufacturers, the technical specifications produced by
administrations and the know-how of contractors have made it possible to develop effective equipment
which is increasingly well suited to soil treatment, whether it is performed in situ or in a plant.
– 42 –
To facilitate selection of the right equipment, the contract manager and the contractor can refer to:
• The standards that lay down the terminology and the principal technical specifications;
• The technical assessments published by the CFTR and, in the case of some equipment, certificates of
technical capacity (CATM published by the CFTR) which state the suitability and performance levels
which may be attained.
The manufacture of treated soil mixes involves the following specific operations:
Adding binder
For in-situ treatment, the binder can be added in powdered form to the surface of the layer to be treated,
using a spreader.
It may be possible to add the binder in the form of a suspension (water + hydraulic binder) prepared in a
mobile mixer and injected directly into the mixing chamber.
In the case of treatment in a plant, the binder is carried by the auger feeder from the silo either to the
conveyor belt that transports the materials or directly into the mixer.
Environmental protection, in particular with regard to binder dust emissions, must be taken into account: the
appropriate measures for each type of equipment must be applied, perhaps with low dust emission binders.
Mixing
For in-situ treatment, mixing must be performed with horizontal shaft soil pulverizers.
This makes it possible to disperse the binder within the entire volume of the material to be treated and
achieve the desired fineness.
The quality of mixing will depend on the direction and the speed of rotation of the rotor, the travel speed of
the machinery, the shape and the number of the tools, how they are arranged on the rotor, their state of wear
as well as the volume of material in the mixing chamber and the position of the paver shutters.
For treatment in a plant, a fixed mixing plant is to be used.
The quality of mixing will depend on the linear speed of the tools, their shape, their number, how they are
arranged on the rotor (reverse paddles), their state of wear and the volume in the mixing chamber as
determined by the position of the retention trap.
As the mixing plant does not generally increase the fineness of fine clayey soils, it may be necessary to
prepare the soils specifically (loosening, pretreatment with lime). The desired grading of the manufactured
mix (Dmax) may be obtained by placing grids on the feed hoppers to remove large particles.
3.3.1 - The level of quality of the treatment equipment for pavement base layers
General comment: only speed-related spreaders are permitted for the treatment of soils for pavement base
layers are. They may be fitted with a system that provides information about the surface area treated every
day in order to check the daily spread rate as a function of the tonnage of binder that is spread.
The specification and acceptance of the equipment for a given in-situ treatment project with a hydraulic
binder may be performed on the basis of 2 criteria for powdered binder spreaders, one criterion relating to
sprinklers and four criteria to soil pulverizers.
These criteria enable the quality of the plant to be characterized.
– 43 –
Powdered binder spreaders
• C: uniformity of binder spreading (Coefficient of variation Cv expressed in %);
• V: possibility of checking the width over which the binder is spread.
Table 29 shows how the various criteria are rated:
Rating of the criteria for binder spreading
CRITERION
C
V
Uniformity of binder spreading
(in %)
Possibility of varying the width of
spreading
3
2
1
Cv ≤ 5
5 < Cv ≤ 10
Cv > 10
OUI
NON
NON
Table 29: rating of the criteria for binder spreading
Comments
The standard NF P 98-115 [33] for the construction of pavement foundations stipulates that the use of plant
with a coefficient of longitudinal variation greater than 10 % is prohibited (shaded area of Table 28).
Photo 1: binder spreader (source: Colas.SA)
Sprinklers
• W: quality of sprinkling
Table 30 shows the ratings that are applied for this criterion:
Rating of the criteria for sprinkling
CRITERION
W
3
Type of sprinkler
Plough
2
Fine jet spray bar
1
Fishtail sprinkler
Table 30: ratings for the sprinkling criteria
Comment
For the treatment of soils for pavement base layers, fishtail sprinklers are prohibited (shaded area in Table
30).
– 44 –
Photo 2: sprinkling with a plough (source: Lhoist)
In-situ mixing plant
•
•
•
•
H: is the quality of homogenization of the material and binder;
E: is the control of the depth of treatment;
I: is the presence of the water injection device;
L: is the proportion of binder in suspension form (water + hydraulic binder).
Table 31: shows the ratings that are applied for this criterion:
CRITERIA
Ratings for the criteria of in-situ mixing
3
2
1
H
Homogenization of the material
with the binder(s)
Vertical and transverse
homogenization (associated mixer)
Vertical homogenization
only
Limited homogenization
E
Control of depth of treatment
Adjustment and control of depth
with an additional function that locks
the rotor at the correct depth(1)
Adjustment and control of
thickness
Adjustment of thickness
I
Possibility of injecting water into
the mixing chamber
Pump with variable flow that is
proportionate to the travel speed
and a variable width spray bar
Pump with a variable rate of
flow that is proportionate to
the travel speed
No automatic control
Binder spread in the form of
suspension (water + hydraulic
binder)
Pump with variable flow that
depends on the speed of translation
or the weight of the treated material
+ flow meter (water) and weighing
(binder)
Pump with a variable rate
of flow that is proportionate
to the travel speed or the
weight of material to be
treated and volumetric
meter
Pump with a variable
flow without automatic
control
L
Table 31: ratings for the criteria for in-situ mixing
(1) This locks the mixing chamber at a certain depth stops it from rising in the event of an excessive increase in the rotor torque. The
rotor can only be raised manually by the operator.
N.B.
The standard NF P 98-115 [33] for the construction of pavement foundations stipulates that the machine
must have a horizontal rotor and possess a working depth display. The spraying systems (for water or
slurries) must be accurate to within 2%. For example, a coefficient of variation Cv greater than 5 % for the
depth (criterion E) is equivalent, at the structural level, to a reduction in thickness of approximately 10%.
– 45 –
Photo 3: in-situ mixing of treated material (source: Colas.SA)
Manufacturing plant
Depending on their dosing, control and automation systems, manufacturing plants may be classified into two
levels; level 2 corresponds to a plant with better performance than level 1.
Table 32, which has been taken from the standard NF P 98-732-1 [47], sets out the requirements for each
level for each function.
Requirements to be met according to the level of the mixing plants
Function
Level 1
Level 2
Dosing of chippings with a maximum fine
particle content (< 80 μm)
<2%
Continuous volumetric doser
Continuous volumetric doser with, as a minimum,
continuous measurement of the speed of the belt with the
idler pulley
Dosing of chippings with a maximum fine
particle content (< 80 μm) > 2 %,
Continuous volumetric doser
Continuous weighing doser
Sands, moist binders, powders
Checking of the moisture content of the
mixture or the sand
Continuous (1) ,with results taken into account by the
automatic data acquisition system
Data acquisition
Data acquisition unit (2)
Automatic control
All or nothing detector on each doser
(aggregate and powder)
Compliance with the functions described in the article on
“automatic control” in NFP 98-732-1 [47]
Proportioning of water
Coupled to the mix design and the continuous
measurement of the water content of the constituents (3)
Proportioning of additives
Coupled to the mix design
Variation in overall flow rate
A conjugator that modifies the flow of all the constituents
(4)
(1) this specification is to be applied as soon as the necessary equipment has been developed
(2) a terminal or a computer socket must permit the connection of an additional data acquisition unit in compliance with the standard NF P 98-772-1 [47]
(3) the specification concerning the automatic consideration of the water content of aggregate will be applied as soon as the necessary equipment has been
developed
(4) the specification concerning the coupling of the conjugator to the water flow will be applied as soon as the necessary equipment has been developed
Table 32: requirements to be met according to the level of the mixing plants
Levels of treatment quality
Two levels of treatment quality (AC) are considered for the use of treated soils in pavement base layers.
– 46 –
The AC1 quality level (better than the level of quality AC2) requires the use of machinery with the minimum
characteristics set out in Table 33 (the unshaded part of the Table).
Definition of the level of quality of treatment AC1
Rating or level
3
2
1
C or L
V
H
E
W or I
Manufacturing plant (1)
(1)
No level 3 manufacturing machinery currently exists.
Table 33: definition of the level of the quality of treatment AC1
For example, equipment with a coefficient CVHEW of 23233 has a quality level of AC1.
The AC2 quality level requires the use of equipment with the minimum characteristics set out in Table 34
(unshaded part of the table).
Definition of the level of quality of treatment AC2
Rating or level
3
2
1
C or L
V
H
E
I or W
Manufacturing plant(1)
(1) )
No level 3 manufacturing machinery currently exists.
Table 34: definition of the level of the quality of treatment AC2
3.3.2 - Treatment in situ
Treatment must be performed on the pavement base layer. It must be carried out as follows:
• preliminary moistening of the materials in accordance with the rules in § 4.2.5;
• determination of the surface density of binder to be spread (for example expressed per m2), according to
the density of the in-situ soil and the desired spread rate;
• spreading of the binder with a sprayer whose “C and V” ratings will determine the quality that is likely to
be achieved (AC1 or AC2);
• mixing performed with equipment whose ratings will determine whether class AC1 or AC2 is attained.
Mixing is continued until a soil/binder mixture of uniform colour is achieved whose fineness complies
with requirements (particles smaller than 20 mm). The water content may also be adjusted if necessary.
N.B.
Currently, treatment with hydraulic binders at the borrow pit or the stockpile is in principle not
– 47 –
recommended except for specific applications (in particular when access is difficult for treatment machinery,
for example in areas where space is lacking and around inspection chambers, poles, obstacles, etc.).
3.3.3 - Treatment in a plant
Rehandling materials at a stockpile before treatment in a plant
In most cases, in order to pass through a plant elements that are larger than 31.5 mm (clumps, agglomerates,
…) to be reduced in size.
The techniques used to crush clumps and agglomerates depend on the nature of the materials:
• the simplest technique is to crush them under the tracks of a bulldozer or the bucket of a shovel (when
enough time is available);
• the most sophisticated techniques use mixing equipment (soil pulverizers) or clod breaking equipment.
The second group of techniques involves materials that are pretreated with lime in particular: in-situ
densification, the loss of water and setting may produce agglomerates which have to be reduced in size when
materials are rehandled at a stockpile.
In all cases, any coarse elements that remain must be eliminated by installing an easily unclogged grid on the
hoppers.
When the stockpile is remote, a buffer stockpile which is sufficiently large for one or two day’s work must
be created at the mixing plant site. It is imperative for this to be protected to avoid variations in water content
(slope, closure of the surface, covering with tarpaulins…).
Manufacture
The manufacturing plant must be designed to take account of the fineness and bulk density of the materials
to be treated to reduce the risks of clogging, jamming, etc..
This means that allowance must be made, as early as the estimate of pricing, for a 30 to 50% reduction in the
nominal rate of the mixing plant (usually determined for treating graded aggregate).
The performance and the running of the plant must make it possible to respond to the following specific
requirements:
• Permit a high proportion of binder
As the binder proportion is usually high compared with treated graded aggregate, the number of silos must
be increased.
It is essential for the binder to be distributed throughout the width of the conveyor belt that transports the
material to the mixer.
• Ensure good flow
Even after pretreatment with lime, some soils (A1, A2, B5, B6…) remain sticky. In order to limit
problems with regard to flow, the following modifications are recommended:
– hoppers should have sides that are more vertical without constrictions and be covered in teflon or
stainless steel plates. An anti-arching device and appropriately positioned vibrators should assist the flow
of materials;
– installing scrapers on the belt scales and conveyor belts in order to reduce fouling.
At the start of works, the proportioning must be calibrated several times during the day’s work in order to
determine the average settings to be used when the plant is in full operation.
• Control of mixing
– 48 –
In view of the cohesive nature of fine soils, a satisfactory mixing time, which is generally longer than that
needed for treated sands and graded aggregate, is required.
For these soils, long shaft mixers are the most effective. With normal mixers, it is necessary to adjust the
vertical angle, the height of the retention trap and sometimes fit some reverse paddles.
New types of mixers which are specifically intended for soil treatment are currently being designed and
developed.
Adjustment of the water content in the mixer must not exceed 1%. Beyond this amount, pre-moistening
must be performed at the stockpile to ensure that the water has enough time to penetrate throughout the
material.
The mixer must be cleaned every day to prevent its fouling.
If a retarder needs to be used, it can be proportioned with the same equipment used for graded aggregate
bound with a hydraulic binder.
3.4 - Transport and laying
All the normal stipulations in the standard NF P 98-115 [33] relating to the transport and laying of the treated
materials apply (protection of the substrate, compliance with the workability time, protection of transported
materials from bad weather, etc.).
3.4.1 - Transport of mixtures
In order to eliminate the risk of contamination from materials whose workability time has been exceeded and
thereby avoid a reduction in transport capacity or imbalances during lifting, the containers must be scraped
and cleaned after each round trip.
If the substrate is used for construction site traffic (capping layer or sub-base layer), it is also important to
make sure that the tyres are clean so as to avoid subsequent problems with regard to the interface conditions.
3.4.2 - Laying
Spreading and preliminary levelling
For material that has already been treated
The aim of spreading is to distribute the imported material to facilitate preliminary levelling.
Preliminary levelling consists of achieving an additional thickness of 10 to 25% more than the thickness of
the loosened material. This additional thickness, which is removed during the final levelling process,
minimizes lamination of the surface and avoids the risk of low zones. The required extra thickness is to be
determined by constructing a test strip or on the basis of experience from previous works.
For material that is treated in situ
In this case, the imported soil must imperatively be precompacted and preliminary levelling performed
before treatment so that the treated depth can be controlled. The height to which the initial levelling should
be performed is to be specified by means of a test strip.
– 49 –
After treatment, the operations will be performed as described in the previous section.
Partial compaction
To ensure the accuracy of the final altimetric adjustment, during partial compaction it is recommended to
apply approximately 80 % of the compaction energy that is required to achieve the final densification target,
or 100% of this energy in the case of materials that are susceptible to lamination.
Type V4 and V5 vibratory compactors (as defined in the standard NF P 98-736 [48]) are not recommended
when the depths of material for compaction are low (to avoid the risk of lamination) and allow the use of
lower energy compactors.
Vibratory tamping roller compactors may be used in the case of soils with a tendency to laminate.
Nevertheless, a preliminary test strip is required to ensure that no imprints are left on the surface.
Maintaining the hydric condition of the surface
This is achieved by spraying water on the surface (using a fine jet water spray bar), during laying or before
the surface protection is applied according to the meteorological conditions.
It does not lengthen the workability time nor correct the water content of the mixture in the mass.
Final levelling
This operation consists of removing the additional thickness left on the entire surface of the layer after partial
compaction.
The materials removed during the final levelling must be taken away from the site and not reused in
pavement base layers.
The levelling tolerances (standard NF P 98-115 [33]) are:
• sub-base layer
: ± 3 cm
• road base layer
: ± 2 cm
It should be noted that, in the case of laminated sheet materials, the currently recommended method is to
remove part of the laminated zone produced during partial compaction during the precise levelling phase,
and then to close the surface with tyred compactors.
Final compaction
The aim of this is to provide the additional compaction which is necessary to achieve the final densification
target and/or redensify the upper part of the compacted surface which may have been disturbed by the final
levelling operation.
– 50 –
3.5 - Surface protection
All treated soil pavement base layers must be provided with surface protection rapidly, at the end of the day
at the latest. In no event can this constitute a final wearing course.
The surface protection must perform the following roles:
• maintain the hydric condition of the treated soil (no evaporation or ingress of water) during the period of
hydraulic setting;
• promote bonding with the layer above it;
• increase resistance to tangential stresses generated by the construction site traffic it will carry;
• reduce slipperiness during rain;
• minimize dust emissions from construction site traffic.
Choice of a suitable surface protection will depend on the roles assigned to it, the nature of the treated soils,
and the mechanical and climatic stresses to which it is subjected.
3.5.1 - Characteristics related to the nature of the treated soils
In the case of a bituminous surface dressing laid on fine and sandy treated soils, embedment (1) is frequently
essential in order to ensure the surface protection is well anchored in the treated soil.
For treated soils with a good granular skeleton after compaction, no specific measure is generally necessary
to assist bonding of the surface protection.
3.5.2 - Mechanical stresses
Depending on the cumulative traffic carried during the works, the mechanical stresses can be classified by
order of increasing aggressiveness as shown in Table 35.
Level of aggressiveness
Cumulative PL traffic in each direction
A
Less than 20 PLs
B
20 to 500 PLs
C
Over 500 PLs
(Based on GTS, 2000 edition [4] )
Table 35: aggressiveness classes according to the traffic carried by the treated layer before laying of the next layer
In cases A and B, the level of aggressiveness is increased by one class if speeds exceed 60 km/h and on bends.
3.5.3 - Climatic stresses
Before being covered by the next pavement layer, treated soils which are covered by the surface protection
are exposed to climatic stresses.
(1)
embedment consists of spreading and setting entirely crushed chippings (code Ang.1 according to the standard XP P 18-545[76] in the surface of
the treated layer, after final compaction. The chippings should have good hardness characteristics (Los Angeles value less than or equal to 30), be
large (14/20 mm or more) and have a spread rate such that approximately 30 to 50% of the surface area is covered. Embedment must be performed
before the end of the workability time by 2 or 3 compactor passes and may be assisted by spraying water over the surface (approximately 1 litre/m²).
About half of the height of the chippings should be set into the material.
– 51 –
As for traffic, a classification of exposure levels in order of increasing severity is given in Table 36.
Level of exposure
Season
Duration of exposure
0
Any
≤ one week
1
Spring-Summer
≤ one month
2
Spring-Summer
≥ one month
3
Autumn
> one week
4
Autumn and Winter
> one week
Table 36: level of exposure of the surface protection to climatic stresses
3.5.4 - The different types of surface protection
The types of surface protection are mainly the same as those described in the GTS. They are shown in
Table 37.
Name
Mix (per m2)
Remarks
0.8 to 1.1 kg of emulsion*
More effective against drying than a curing
+
coating for long exposure times.
Sealing coat
(ES)
Small chippings in excess**
Single surface dressing
(EM)
1.3 to 1.6 kg of emulsion
+
7 to 8 litres of 4/6 chippings** or 9 to 10 litres
of 6/10 chippings**
The choice of chippings depends on the aggressiveness
of the traffic.
The emulsion spread rate may be increased by 5 to 10%
depending on the roughness of the substrate
.
Double surface dressing
(EB)
1st layer:
1.1 to 1.3 kg of emulsion*
10 to 11 litres of 10/14 chippings**
The amount of emulsion in the first layer must be adjusted
on the basis of the roughness of the substrate.
2nd layer:
1.5 kg of emulsion*
Pre-chipped surface
dressing
8 to 9 litres of 10/14 chippings **
(EP)
+
2 kg of emulsion*
+
This protection is comparable to that obtained by applying
a single surface dressing on a subgrade in which
chippings have been embedded beforehand.
* The surface density for a cationic emulsion with a bitumen content of 65%.
**The Los Angeles value of the chippings must be ≤ 30 and their cleanliness (fraction passing a 63 micron screen) ≤ 2 %
Table 37: types of surface protection
– 52 –
Photo 4: surface protection with prechipping
(source: Lhoist)
Photo 5: chipping (source: Cimbéton)
The effectiveness of these surface protections with respect to their possible roles is summarized in Table 38.
Roles
Type of surface
protection
Bonding of the upper layer
Protection
Mechanical
protection
Reduction of
dust
emissions
=
=
+
-
+
=
+
+
=
++
+
++
+
=
++
++
++
Protection
against
evaporation
against water
ingress
Hydraulically
bound base
layer
GB or
BB
Sealing coat ES
=
=
-
Single surface dressing EM
=
=
Double surface dressing EB
+
Prechipped surface dressing
EP
+
++ very effective + effective = moderately effective - not very effective - - ineffective
Table 38: the functions and effectiveness of the different types of surface protection
Dust emissions from a treated soil pavement layer are a sign of deterioration: a non-confomance report must
be issued.
3.5.5 - Choice of the type of surface protection
In order to guarantee the durability of the protection while the layer is exposed, the types of surface
protection set out in Tables 39 and 40 are used, depending on the level of aggressiveness of the traffic, the
climatic exposure and the nature of the layer (sub-base layer or road base layer).
– 53 –
Sub-base layer
of construction site
traffic
Level of climatic exposure
0
1
2
A
3
4
ES
B
ES
ES
EM
EM
EM
C
ES
EM
EM* or EB
EB
EB or EP**
3
4
EB* or EP**
EB* or EP**
* on gravelly soils
** on sandy soils without embedment
Table 39: choice of type of surface protection for sub-base layers
Sub-base layer
of construction site
traffic
Level of climatic exposure
0
1
2
A
EM
B
EM
C
EM
EM
EB* or EP**
* prefer EB for waterproofing, particularly in the case of fine soils
** on sandy soils without embedment
Table 40: choice of type of surface protection for road base layers
It should be noted that the surface must be sprayed with water before any bitumen emulsion-based surface
protection is applied and that a certain time interval is required before the treated layer is opened to traffic.
Flowchart of soil treatment for pavement base layers
1st case Treatment with a hydraulic binder in a plant of a natural soil or a soil that has been pretreated with
lime prior to laying.
2nd case Importation of natural soil or the lime-pretreated soil for in-situ treatment with a hydraulic binder.
3rd case Double in-situ treatment with lime and a hydraulic binder.
– 54 –
APPRO: Importation of material (onto the laying site)
ARROS: Sprinkling of the water on the mixture to adjust the water content
CLOU Embedment
COMP par: Partial compaction (approximately 80% of the required energy)
COMP fin: Final compaction
EPAND: Spreading of the treatment product (several passes if necessary)
FAB: Manufacture of the mixture (in a plant or at the stockpile)
FERM: Closure of the surface by light compaction (2 passes)
HUM: Moistening to maintain the water content
MALAX: Mixing the soil with a treatment product and, if necessary, moistening under the mixing bell
PREPAR: extraction and preparation of the soil (homogenization in situ or at the stockpile, breaking clods if
necessary,…)
PRE-REG: preliminary levelling of the subgrade (between 10 and 25 % above the final level)
PRO SUP Surface protection
REGAL: Spreading the imported material
REG FIN: Precise levelling
SCAR: Scarification
This operation is not systematic and depends on the conditions at the construction site
A time interval may be required to obtain the desired effects
Operations which must be performed while the mixture remains workable
– 55 –
and/or hydraulic binders– Application to the construction of pavement base layers– Technical guide
3.6 - Quality control
The construction of a pavement base layer is always of fundamental importance.
This is because the quality of the pavement base layers, where the highest mechanical stresses are concentrated
(vertical deformation and tensile stress at the base of the treated layer) are concentrated, determine the
pavement’s service life.
This explains why this guide, while describing the technical choices and obligations, lays so much emphasis on
the minimum content of the quality assurance checks, in order to provide the most rigorous possible framework
for the performance of works.
Quality management plays a role from project design to acceptance of the works, particularly with regard to the
following points:
• Geotechnical surveys: these must determine or confirm:
– the soil classification (NF P 11-300 [16]),
– its class of uniformity,
– the current hydric conditions,
– the quantities of uniform soils that are genuinely available.
• Treatment products: these must be standardized or be covered by a technical assessment (or a similar
procedure);
• Treatment study: the aim of this is to determine the design of the “soil + binders” mixture which provides
the mechanical characteristics that are to be applied during design;
• Design: the mechanical characteristics of the treated soil – tensile strength (Rt) and modulus of elasticity (E) –
must be correctly measured (and, above all, not overestimated);
• The fatigue and interface conditions to be considered are those specified in this guide;
• Construction equipment: this must be compatible with the laboratory hypotheses and the required quality;
• Interface quality: the quality of bonding depends above all on the care taken when performing works.
Maintaining the hydric condition of the surface of the treated layers, avoiding dirt, reducing surface lamination
and the appropriate choice of surface protection greatly reduce the risk of debonding in the long term.
Table 41 (Construction site checks) guides decision-makers and contractors through the practical actions that
must be performed for each stage in the construction of treated soil pavement layers.
When these recommendations are identical with those in the standard NF P 98-115 [33] or in part C3 of the
technical guide "Traitement des sols à la chaux et/ou aux liants hydrauliques" (GTS - January 2000) [4], they
have not been repeated in detail in this table.
Rigorous application of this table will greatly help to guarantee the quality of the structure.
– 56 –
ACTIONS
PHASE
OF
WORKS
BEFORE
PERFORMANCE OF
THE WORKS
- PREPARATION OF
WORKS
NATURE
QUALITY
ASSURANCE
PLAN (PAQ ):
DRAFTING
AND
PRESENTATION
MINIMUM FREQUENCY (indicative)
NATURE
COMMENTS
The PAQ is a document:
that is drafted in conformity with the terms of
the contract and the content of the SOPAQ.
That can, if necessary, be supplemented or
modified as works progress.
A record of the general organization (organizational
chart of the construction site, list of those involved,
subcontractors, suppliers, equipment, materials and
a list of sensitive points and stoppage points)
that must be endorsed by the contract manager
(initial document and subsequent modifications)
Monitoring documents
Nonconformance sheets (mix design studies)
TREATMENT:
geotechnical investigation specified in the
contract and used in the mix design studies
The type and frequency of testing
VERIFICATION
This verification is performed by the contractor
as part of its "Additional investigation":
OF NATURE
AND STATE
1 PAQ for each construction site
Construction procedures
The PAQ (or a procedure) must specify:
FOR
OTHER WORKS
The PAQ features, in particular:
Checking that the real characteristics are
identical with those defined in the
MATERIALS
SMALL-SCALE WORKS
(approximate volume of
pavement materials
Vchaussées<5000 m3 )
Identification as described in the GTR [5] and
NF P 11-300 [16]:
particle size analysis:
The frequency of sampling,
The measures to be taken in the event of
divergence from the initial hypotheses
(humidification, aeration, additional treatment,
rejection …)
Specifying the average value and dispersion
of the nature
NF P 94-056 [23]
and state characteristics.
Methylene blue value (VBS) NF P 94-068 [24]
Proctor test: NF P 94-093 [25] ou
Fine soils A
- VBS:
1 test for every 1 000 m3 extracted
- OPN & IPI for the extreme VBS values:
2 tests for every construction site
NF EN 13286-2 [64]
1 test for every 5 000 m3
Sandy-gravelly soils B
Immediate bearing capacity (IPI):
- fraction passing 0.08 mm / 2 mm / 31.5 mm screens:
NF EN 13286-47 [67]
1 test for every construction site
Moisture content: NF P 94-049-1 [19], NF P 94049-2 [20] and NF P 94-05 [21]
1 test for every 1000 m3
- VBS:
1 test for every 1 000 m3
Type A and B soils
– 57 –
TTreatment of soils with lime
ACTIONS
PHASE
OF
WORKS
NATURE
NATURE
COMMENTS
SMALL-SCALE WORKS
pavement materials
OTHER WORKS
- moisture content: 1 for every 1000 m3
- IPI:
PRODUCT
APPROVAL:
BINDERS
BEFORE
EXECUTION OF THE
WORKS
decision-making:
Lime, Cement
Hydraulic binder
the terms of the contract requirements
OTHER PRODUCTS
CONSTRUCTION
SITE
Chippings for surface
dressings, emulsion or
surface dressing binder
CONSTRUCTION
EQUIPMENT:
PREPARATION OF
Principal documents required for
Decision taken by the project manager, on the
basis of:
- PREPARATION OF
conformance of the data sheet
standards (NF mark if any)
mix design studies
the request for approval presented by the
contractor (accompanied by the documents
needed to make the decision).
1 approval for every product and every source
Product data sheet
standards
data sheet (for each type of emulsion)
Data necessary for decision-making:
Decision by the project manager, based on:
ACCEPTATANCE OF
CHOICE
the terms of the contract and
Appropriateness of type of equipment to the goals
and construction technique
documents proposed by the contractor
Equipment data sheet
PRODUCTS
DELIVERED:
Checking the conformance of the acceptance
sheet
1 acceptance for every machine
(on condition that subsequent validation is performed after the
suitability control test)
Dimensioning of plant
Periodic checks by the supplier (in conformity with
its PAQ) results sent to the contractor
– 58 –
1 supplier internal checksheet
systematic checks of the product delivery sheets
ACTIONS
PHASE
OF
WORKS
THE
PERFORMANCE OF
WORKS
NATURE
NATURE
COMMENTS
quicklime: reactivity - NF EN 459-2 [59]
CONFORMANCE
t°C > 60° C in less than 25 min
For all binders: sample storage in hermetically
sealed containers under dry conditions
(CCTG - part 25)
[1]
EQUIPMENT:
Verification of the conformance of the
acceptance sheet:
The characteristics are the same as those that
permitted acceptance
SUITABILITY
Regularity and precision of the rate of spread:
The measurement method may be based on that
described in Annex 6 of the G.T.S [4]
Cv < 10 %
- Cv (Tolerance in NF P 98-115 [33])
Binder spreader
Mixer
e≤5%
- precision: e
Speading width
To be measured and described if width variable
Condition of tools (teeth, blades)
visual check
Mixing depth
measurement and calibration (visible reference)
PREPARATION OF
THE
PERFORMANCE OF
Sprinkler
Regularity and precision of the rate of
spreading (flow meters and control system in
the case of a sprinkler-plough)
The measurement method may be based on that
described in Annex 6 of the G.T.S [4]
WORKS
Mixing plant
Adjustment and control of devices:
Measurement of:
NF P 98-115 [33] (article 8.2.1.3)
- regularity and precision of the rate of spread
NF P 98-744.1 [49] to 744.5 [50 to 53]
- speed of the conveyor belts (materials, binders,
water)
[1]
OTHER WORKS
1 test for every 100 tonnes
delivered
One 2kg sample:
for every construction site and
product
For every 250 tonnes
(cement, HRB) delivered
For every 100 tonnes (lime)
delivered
coefficients of variation
(CCTG - part 25)
SMALL-SCALE WORKS
pavement materials
– 59 –
The spreaders and compactors The check to be carried out
before or during the
used must have been checked in
suitability control test.
the three months before the works.
Other equipment, must have been It must be repeated if the
equipment is changed (or
checked within the 12 months
repaired in a way that might
before the works
alter its characteristics).
ACTIONS
PHASE
OF
WORKS
NATURE
NATURE
Compactor
calibration, adjustment and classification:
COMMENTS
SMALL-SCALE WORKS
pavement materials
OTHER WORKS
mass
eccentric moment and frequency
NF P 98-761 [55]
contact pressure with soil
NF P 98-760 [54]
Emulsion sprayer
regularity and rate of spreading
NF P 98-275-1 [44]
Chipping spreader
regularity and rate of spreading
NF P 98-276-1 [45] et 2 [46]
Topographical
adjustment equipment
coupled to the grader
Accuracy and regularity of altimetric
measurements
Topographic apparatus – of the GPS/DPS type –
checked according to a method specified by the
manufacturer
SUBSTRATE:
CHECKING
(Technical guide
"Conception des
structures de
chaussées neuves")
Checks before the layer to be treated is laid:
modulus of the untreated substrate (plate,
Dynaplaque)
NF P 94-117.1 [26] and 2 [27] (plate, Dynaplaque)
deflection (Benkelman beam, deflectograph or
NF P 98-200.1 [35] to 200.7 [36 to 42] (Benkelman
curviameter)
beam, deflectograph or curviameter)
Altimetry of the substrate
Topographical survey
or 1 passage per traffic lane
(deflectograph or
curviameter)
3 tests: centre + edges
for 250 m2
– 60 –
for 150 m2
ACTIONS
PHASE
OF
WORKS
PREPARATION OF
THE
PERFORMANCE OF
WORKS
NATURE
NATURE
COMMENTS
Check that the equipment and methods
described in the PAQ and (perhaps) tested by
the contractor meet the quality requirements
(contract) sufficiently well as well as the
contractor’s stated work rate
This should apply a specific procedure
SMALL-SCALE WORKS
pavement materials
which will describe, in particular, the
calibrate the additional thickness (the thickness of
preliminary levelling) to be removed during precise
levelling (because of lamination, correction of the
surface state...)
- type of material
- type of treatment
NB: the precise methodology
is described in the
"Retraitement des
chaussées" [6]
compaction: speed and number of passes that
provide the require density
TEST
OTHER WORKS
1 test (reference strip) for
each:
methodologies used to:
mixing: obtaining the desired fineness and
uniformity
SUITABILITY
CONTROL
(CCTG - fascicule n°
25)
conduct of all the operations (treatmentcompaction) during the workability time
[1]
Treatment in situ
Spreading the binder
wetting
Treatment in a mixing plant
Precision and regularity of flows
Taking account of changes in moisture content
(particularly on the journey between the mixing
plant and the construction site)
Verification that construction complies with the
specifications (contract - study)
DURING THE
PERFORMANCE OF
WORKS
Binder proportioning:
TREATMENT:
(CCTG - part° 25 et
CCTP "type")
[1]
(mass spread per m2)
Weighing checks (and / or):
on a tarpaulin or in a container (1,00 or 0,50
CONFORMANCE
m2)
or direct reading (spreader fitted with an on-board
weighing system) with continuous recording
of the spreader (in relation to the treated surface
area)
– 61 –
2 series (of 3 weighing operations)
every day
3 series ((of 3 weighing
operations) every day
Checking of the average daily spread rate: the mass of binder
spread per unit area treated
Spreader weighed once every day
Spreader weighed three
times every day
ACTIONS
PHASE
OF
WORKS
NATURE
NATURE
COMMENTS
Treatment in situ
thickness for treatment
Measurement of thickness or raising of the mixer
bell (tolerance + or – 2 cm; see.NF P 98-115) [1]
Reading the mixer scale or direct reading (for a
mixer with an on-board checking system)
DURING THE
PERFORMANCE OF
WORKS
Treatment in a mixing
plant
Regularity of manufacture (material, binders,
water)
Hydric condition (targeted W >WOPN -1):
Measurements of the moisture content during
the treatment phases using rapid methods
OTHER WORKS
4 measurements per day (unannounced sampling)
Method: NF P 98-115 [1]
Specification and checking of warning and stopping
limits: NF P 98-105 [30]
Daily report on the operation of the mixing plant
Binder dispersion: colour
continuous visual
D of the material < 20 mm
4 measurements per day (unannounced sampling)
Uniformity of the mixture
(CCTG - fascicule n°
25 et CCTP "type") Treatment in situ and a
mixing plant
[1]
SMALL-SCALE WORKS
pavement materials
NF P 94-049.1, NF P 94-049.2 [20] and NF P 94050 [21]
Nuclear density gauge – moisture meter
3 tests for every phase of treatment
3 tests for every phase of
treatment for every 1000 m3
1 measurement for every 250 m2
with a minimum of 10
measurements
1 measurement for every
250 m2 for each traffic lane
(after calibration using oven methods)
other methods (gas burner…)
COMPACTION:
Checking of the compaction rate
(in-situ dry density compared to the reference
Proctor optimum used in the study)
CONFORMANCE
Measurement of the average density in situ with a
nuclear density gauge
Calculation of a specific Q/S (possibly)
1 per day and per section
Checking of the level:
LEVELING AND
THICKNESS OF
TREATED LAYERS:
CHECKING
Altimetric adjustment of the substrate
Thickness of the layer after preliminary levelling
(imported layer treated in situ)
Conventional topographical equipment and
methods
Final levelling after treatment and compaction
1 point per profile (centre)
2 points per profile (centre +
staggered measurements at
edges)
staggered measurements at edges)
R + L edges
– 62 –
ACTIONS
PHASE
OF
WORKS
NATURE
SURFACE
PROTECTION:
VERIFICATION
AFTER THE
NATURE
COMMENTS
Applied products: aggregate for embedment
and bitumen emulsions:
see "Product approval"
spreading: measurement of chippings and emulsion
in a container
NF P 98-275-1 [44] and 98-276-1 [45] et 2 [46]
NB: when the surface will be used by construction
site traffic the surface dressings are to be checked
as laid down in the Surface Dressings (Enduits
Superficiels) technical guide and NF P 98-160 [34]
(type ESU2)
Conventional topographical equipment and
techniques
1 series (of 3 measurements)
for each construction site
every week
3 points per profile (L, centre, R)
Longitudinal profile analyzer measurements:
Longitudinal evenness
Acceptance test if stipulated in the contract
Deflection (after at least 28 days)
1 passage per traffic lane
Informatory test otherwise
Checking the quality and uniformity of the treated
layer: detection of anomalies
MECHANICAL
PERFORMANCE
OTHER WORKS
Quantities and spread rate
ACCEPTANCE
(NF P 98-115) [33]
SMALL-SCALE WORKS
pavement materials
quality
geometry: altimetry – planimetric representation
WORKS
NB: values > 50/100 mm mist be considered to
reflect anomalies
1 passage
1 test –Benkelman beam - per
profile
of a deflectograph or
curviameter – for each traffic
lane
Mechanical strength measured on core
samples: the values measured on core samples
The overall quality of a layer results from correct
taken from the site (strengths, density, length)
implementation of all the checks performed during
must not be used for acceptance of a treated
the works
layer: these tests must only be used for
information purposes
– 63 –
ACTIONS
PHASE
OF
WORKS
NATURE
NATURE
COMMENTS
SMALL-SCALE WORKS
pavement materials
OTHER WORKS
The documents include, in particular:
CHECKING
Finalized after the acceptance operations
the PAQ documents (monitoring sheets,
checksheets, reception documents, suitability
control test sheets, non-conformance reports …)
1 check file for each construction site
summarizing documents (plans, longitudinal
profiles, diagrams, photos…)
the treatment of cases of non-conformance
Table 41: construction site checks
– 64 –
4 - Abbreviations - symbols - definitions
AR
Subformation (this is the subgrade that is provided at the end of earthworks on which, if necessary,
a capping layer will be laid)
Aci
b
BB
CAM
CATM
The level of quality of soil treatment
Slope of the fatigue line of the material expressed as a bilogarithmic equation
Asphalt concrete
Average coefficient of aggressiveness of a truck compared to the standard axle
Certificat d’aptitude technique des matériels routiers (Certificate of Technical Suitability for Road
Machinery)
Cahier des clauses techniques générales (General Technical Specifications). These lay down the
technical requirements for all services of a given type. The CCTG - Travaux (decree of 14 June 1982
modified) applies to all contracts for works. It is in a number of different parts that apply to different
types of works or different trades: earthworks, concreting, metal joinery, etc.).The CCTG are based
on technical standards, for example NF P 98-115 for works involving treated soils
Cahier des clauses techniques particulières (Specific Technical Specifications) These are the
contract documents which specify, for the specific project in question, all the technical measures
that are required to provide the quality sought by the project manager, in addition to the CCGT.
Comité français pour les techniques routières (French Road Engineering Committee)
Load capacity
Coefficient of variation
Dossier de consultation des enterprises (Tender invitation documents). These are all the documents
that are sent to firms in order for them to make their tenders)
Maximum screen size for which the passing fraction is between 80 % and 99 %
Maximum size of the largest particles in a soil (according to NF P 1130)
Elasticity modulus, expressed in MPa
Range of measurements
Relative range of measurements (ratio between the range of measurements e and the average
measurement m)
Double surface dressing
Equivalent standard axle load
Single surface dressing
Pre-chipped surface dressing
Sealing coat
Wearing course
Fiche technique sol (Soil Data Sheet)
Friability of sands
Road base asphalt
Graded aggregate bound with a hydraulic binder
Unbound graded aggregate
Graded aggregate bound with a hydraulic binder
Réalisation des remblais et des couches de forme, guide technique (Technical guide for the
construction of embankments and capping layers)
Guide technique pour le traitement des sols à la chaux et/ou aux liants hydrauliques (Technical
guide for the treatment of soils with lime and/or hydraulic binders)
Volumetric swelling expressed in %
Hydraulic road binder
CCTG
CCTP
CFTR
CU
Cv
DCE
D
Dmax
E
e
er
EB
Eq
EM
EP
ES
ESU
FTS
FS
GB
GH
GNT
GTLH
GTR
GTS
Gv
HRB
– 65 –
IdF
Ie
IPI
Ip
kc
kd
kr
ks
Li
LA
LCPC
LTCC
MB
MDE
MJA
MPa
MTLH
NE
OPN
OPM
PAQ
PFi
PST
PTAC
PL
Q/S
rc
Rc
Rt
Rit
RTR
ρd
ρde
ρdOPN
Sétra
Sh
SN
SOPAQ
SOIL Ti
Ile de France (Greater Paris Region)
Binder content of the study formula
On-site bearing ratio which expresses the extent of shear failure of a soil specimen compacted with
standard Proctor energy as a percentage of its initial thickness
The plasticity index of a soil, which characterizes its clay content
Calibration coefficient
Coefficient that takes account of the discontinuities in rigid pavement structures
Coefficient that adjusts the value of deformation or allowable stress as a function of the design risk
and dispersion factors
Coefficient that takes account of local variations in the bearing capacity of the underlying unbound
layer
Lower limit of the aggregate specification envelope
Los Angeles value in %
Laboratoire central des ponts et chaussées (French Central Public Works Laboratory)
Silts treated with lime and hydraulic binders
Cleanliness as measured by the methylene blue test
Micro-Deval coefficient in the presence of water, expressed in %
Average annual Daily Traffic, used to calculate the Traffic level Ti
Megapascal
Materials bound with hydraulic binders
Equivalent number of standard axles corresponding to the PL traffic
Standard Proctor Optimum
Modified Proctor Optimum
Quality Assurance Plan
Bearing capacity class i of the pavement subgrade
Upper part of earthworks
Total gross weight
A heavy vehicle, considered, since the publication of the standard NF P 98-082 as a vehicle with
total weight of 3.5 tonnes or (PTAC ≥ 35 kN). The previous definition of a heavy vehicle was any
vehicle with a load capacity of 5 tonnes or over (CU ≥ 50 kN)
Amount of material per unit surface
Design risk
Unconfined compressive strength expressed in MPa
Direct tensile strength, expressed in MPa
Indirect tensile strength, expressed in MPa
Recommandation pour les terrassements routiers(Recommendations for road earthworks).
Dry density expressed in t/m3
Design dry density of the soil or material expressed in t/m3
Standard Proctor Bulk density. This is the maximum dry bulk density measured when a soil or a
material is compacted with the standard Proctor energy. It is obtained when the moisture content of
the soil is equal to WOPN expressed in t/m3
Service d’études techniques des routes et autoroutes (Technical Department for Transport, Roads
and Bridges Engineering and Road Safety)
Standard deviation of the thickness of laid pavement materials, expressed in m
Standard deviation of the logarithm of the number of cycles leading to fatigue failure (fatigue law).
Schéma organisationnel du plan d’assurance de la qualité (Organizational Chart of the Quality
Assurance Plan)
Quality class of the soil on the basis of Rt and E
– 66 –
t°C
εt
εz
σad
σt
σ6
Ti
TCi
Vchaussée
VBS
W
We
WOPN
Reactivity of the lime measured according to the standard NF EN 459-2
Maximum tension-compression deformation in the horizontal plane
Maximum vertical deformation
Allowable stress at the base of a layer of materials, expressed in MPa
Maximum tension compression stress in the horizontal plane, expressed in MPa
Stress at which the bending tensile failure of a 360 day-old specimen is obtained after 106 cycles,
expressed in MPa
Traffic class corresponding to a certain number of heavy vehicles per day in each direction on the
most travelled lane, during the year the road is opened to traffic. It is used for geometric design and
the selection of pavement materials.
Cumulative traffic class corresponding to the cumulative number of heavy vehicles in each direction
on the most travelled lane that the pavement will have to withstand during its design life. It is used
for pavement design.
Volume of pavement materials
Methylene blue value of a soil (this is expressed as the mass of methylene blue that can be absorbed
by 100 g of soil; the higher the clay content of the soil the higher its value), expressed in g of
methylene blue per 100g of soil.
Moisture content
Design moisture content of the soil or material expressed in %
Standard Proctor Optimum moisture content of the soil or material (this is the moisture content that
provides the ρdOPN when the soil or a material is compacted with Standard Proctor energy),
expressed in %
– 67 –
5 - Bibliography
General regulations
[1]
Cahier des clauses techniques générales (CCTG) – fascicule 25 - Exécution des couches de chaussées.
(General Technical Specifications (CCTG) –Part 25 – Construction of Pavement Layers.
National guides
[2]
Manuel de conception des chaussées neuves à faible trafic, guide technique
(Design manual for low traffic roads, technical guide),
[3]
Conception et dimensionnement des structures de chaussées, guide technique
(Technical Guide for the Design of Pavement Structures)
[4]
Traitement des sols à la chaux et/ou aux liants hydrauliques – Application à la réalisation des remblais et
des couches de forme, Guide technique, Sétra/LCPC, 2000 (referred to as the GTS),
(Treatment of soils with lime and/or hydraulic binders – Application to the construction of embankments and
capping layers, Sétra/LCPC Technical Guide.
[5]
Réalisation des remblais et des couches de forme (dit GTR), guide technique (fascicules 1 et 2),
Sétra/LCPC, 2éme édition, juillet 2000, réf. : D9233.
(Construction of embankments and capping layers (known as the GTR), Technical Guide, Parts 1 and 2), 2nd
Edition, July 2000, ref. D9233).
[6]
Retraitement en place à froid des anciennes chaussées, guide technique, Sétra/CFTR 2003, réf. D0309
(Cold in-situ retreading of existing pavements, Sétra/CFTR Technical Guide, 2003, ref. D0309
[7]
Catalogue des structures types de chaussées neuves-guide technique, Sétra/LCPC 1998
(Catalogue of New Standard Pavement Structures, Sétra/LCPC Technical Guide 1998).
Regional guides
[8]
Utilisation des matériaux de Haute-Normandie, guides techniques et monographies, guides techniques
« Les limons », « Les granulats marins », mars 2000, Région Haute-Normandie, UNICEM Normandie,
Préfecture Haute-Normandie, SPRIR Normandie, CETE Normandie-Centre, DRE de Haute Normandie.
(Use of the materials of Haute-Normandie, Technical Guides and Monographs, Technical Guides “Silts”,
“Marine Aggregate», March 2000, Région Haute-Normandie, UNICEM Normandie, Préfecture HauteNormandie, SPRIR Normandie, CETE Normandie-Centre, DRE de Haute Normandie).
[9]
Utilisation des matériaux de Haute-Normandie, guides techniques et monographies , Monographies « Les
sables albiens », mars 2000, Région Haute Normandie, UNICEM Normandie, Préfecture HauteNormandie, SPRIR Normandie, CETE Normandie-Centre, Dre de Haute Normandie.
(Use of the Materials of Haute-Normandie, Technical Guides and Monographs, Monographs “Albian
sandstones”, March 2000, Région Haute Normandie, Unicem Normandie, Préfecture Haute-Normandie, SPRIR
Normandie, CETE Normandie-Centre, DRE de Haute Normandie).
[10] Guides Techniques pour l’utilisation des matériaux régionaux d’Ile-de-France, guides techniques « Les
limons », « Les sablons », décembre 1996, ARENE d’Ile de France, Préfecture d’Ile de France, Conseil
régional d’Ile de France, UNICEM Ile de France, SPRIR Ile de France.
(Technical Guides for the Re-use of the Regional Materials of the Paris Region, Technical Guides “Silts”,
“Fine sands”, December 1996, ARENE d’Ile de France, Préfecture d’Ile de France, Conseil régional d’Ile de
France, UNICEM Ile de France, SPRIR Ile de France).
[11]
Guides Techniques pour la réutilisation des matériaux régionaux d’Ile-de-France, catalogue des
structures de chaussées de décembre 2003, ARENE d’Ile-de-France, Préfecture d’Ile-de-France, Conseil
régional d’Ile de France, UNICEM Ile-de-France, Sprir Ile-de-France.
(Technical Guides for the Re-use of the Regional Materials of the Paris Region, Catalogue of Pavement
Structures, December 2003, ARENE d’Ile-de-France, Préfecture d’Ile-de-France, Conseil régional d’Ile de
France, UNICEM Ile-de-France, SPRIR Ile-de-France).
– 68 –
[12] Guide technique pour l’utilisation des matériaux régionaux d’Ile de France : valorisation des Excédents
de déblais de travaux publics – décembre 2003, Préfecture de la Région Ile de France, UNICEM Ile-deFrance, SPRIR Ile-de-France, Région Ile-de-France.
(Technical Guides for the Use of the Regional Materials of the Paris Region: Recycling of excess fill material
from public works – December 2003, Préfecture de la Région Ile de France, UNICEM Ile-de-France, SPRIR Ilede-France, Région Ile-de-France).
[13] Guides techniques régionaux Nord-Pas-de-Calais relatifs à la valorisation des déchets et co-produits
industriels, « Les schistes houillers », « les sables de fonderie », mai 2002 PREDIS Nord-Pas-de-Calais,
Ecole Mines de Douai, CETE Nord-Picardie.
(Regional Technical Guides for Nord-Pas-de-Calais for the recycling of industrial wastes and by-products,
“Colliery Shales”, “foundry sand”, May 2002 PREDIS Nord-Pas-de-Calais, Ecole Mines de Douai, CETE
Nord-Picardie).
[14] Utilisation des matériaux en Picardie, guide technique « Les sablons », octobre 2000, Conseil Régional de
Picardie, UNICEM Picardie, Ministère Industrie, Contrat de plan interrégional du bassin Parisien.
(The Use of Materials in Picardie, Technical Guide “Fine sands”, October 2000, Conseil Régional de
Picardie, UNICEM Picardie, Ministère Industrie, Contrat de plan interrégional du bassin Parisien).
[15] Guide pour l’emploi des Matériaux locaux en Champagne-Ardenne, livret pour la technique routière
« Utilisation des matériaux alluvionnaires de la vallée de l’Aisne »,1993, Cellule Economique Régionale
de Champagne-Ardenne .
(Guide for the use of Local Materials in Champagne-Ardenne, Booklet for HIghway Engineering “The use of
alluvial material from the Aisne Vallet”,1993, Cellule Economique Régionale de Champagne-Ardenne).
Standards
[16] NF P 11-300 : Exécution des terrassements - Classification des matériaux utilisables dans la construction
des remblais et des couches de forme d’infrastructure routière.
(Earthworks – Classification of materials for use in the construction of road embankments and capping
layers).
[17] NF P 15-108 : Liants hydrauliques - Liants hydrauliques routiers - Composition, spécifications et critères
de conformité.
(Hydraulic binders – hydraulic road binders - composition, specifications and conformance criteria).
[18] NF P 18-576 : Granulats. Mesure du coefficient de friabilité des sables.
(Aggregates - Measurement of the friability coefficient of sands).
[19] NF P 94-049-1 : Sols - Reconnaissance et essais - Détermination de la teneur en eau pondérale des
matériaux – Partie 1 – Méthode de la dessiccation au four à micro-ondes.
(Soils - Investigation and testing - Determination of moisture content by weight - Part 1: microwave oven
drying method).
[20] NF P 94-049-2 : Sols - Reconnaissance et essais - Détermination de la teneur en eau pondérale des
matériaux - Partie 2 - méthode à la plaque chauffante ou panneaux rayonnants.
(Soils - Investigation and testing - Determination of moisture content by weight - Part 2: heating plate or
radiating panel method).
[21] NF P 94-050 : Sols - Reconnaissance et essais - Détermination de la teneur en eau pondérale des
matériaux – Méthode par étuvage.
(Soils - Investigation and testing - Determination of moisture content - Oven drying method).
[22] NF P 94-051 : Sols - Reconnaissance et essais - Détermination des limites d’Atterberg – Limite de
liquidité à la coupelle – Limite de plasticité au rouleau.
(Soils - Investigation and testing - Determination of the Atterberg limits - Plastic limit test using the
Cassagrande apparatus – Plastic limit test on rolled thread).
[23] NF P 94-056 : Sols - Reconnaissance et essais - Analyse granulométrique – Méthode par tamisage à sec
après lavage.
(Soils - Investigation and testing - Particle size analysis - Dry screening method after washing)
– 69 –
[24] NF P 94-068 : Sols - Reconnaissance et essais - Mesure de la capacité d’absorption de bleu de méthylène
d’un sol ou d’un matériau rocheux - Détermination de la valeur de bleu de méthylène d’un sol ou d’un
matériaux rocheux par l’essai à la tâche.
(Soils - Investigation and testing - Measuring the methylene blue adsorption capacity of a rocky soil or
material- Determination of the methylene blue value of a soil of rocky material by means of the stain test).
[25] NF P 94-093 : Sols - Reconnaissance et essai de compactage Proctor – Détermination des références de
compactage d’un matériau- Essai Proctor modifié - Essai Proctor normal.
(Soils - Investigation and testing. Determination of the compaction characteristics of a soil - Modified Proctor
test - Standard Proctor test).
[26] NF P 94-117-1 : Sols - Reconnaissance et essais - Portance des plates-formes - Partie 1 : Module sous
chargement statique à la plaque (EV2)
(Soils - Investigation and testing - Subgrade bearing capacity - Part 1: plate test static deformation modulus
(EV2)).
[27] NF P 94-114-2 : Sols - Reconnaissance et essais - Portance des plates-formes - Partie 2 : Module sous
chargement dynamique.
(Soils - Investigation and testing - Subgrade bearing capacity - Part 2 Modulus under dynamic loading).
[28] NF P 98-082 : Chaussées - Terrassements - Dimensionnement des chaussées routières - Détermination
des trafics routiers pour le dimensionnement des structures de chaussées.
(Pavements – Earthworks - Road pavement structural design. Road traffic evaluation for pavement structural
design).
[29] NF P 98-100 : Assises de chaussées - Eau pour assises - Classification.
(Road foundations. Water for pavement base layers. Classification).
[30] NF P 98-105 : Assises de chaussées - Fabrication en continu des mélanges-contrôle de fabrication des
graves et sables traités aux liants hydrauliques ou non traités en centrale de malaxage continu.
(Pavement base layers - Continuous manufacture of mixtures - Production control of granular materials and
sands bound with cementitious binders or of untreated granular materials and sands in a continuous mixing
plant)
[31] NF P 98-114 -2 : Méthodologie d’étude en laboratoire des matériaux traités aux liants hydrauliques Partie 2 : Sables traités aux liants hydrauliques.
(Road foundations - Methodology for the laboratory study of materials treated with hydraulic binders. Part 2 :
sands treated with hydraulic binders)
[32] NF P 98-114 -3 : Méthodologie d’étude en laboratoire des matériaux traités aux liants hydrauliques Partie 3 : Sols traités aux liants hydrauliques associés à la chaux.
(Road foundations - Methodology for the laboratory study of materials treated with hydraulic binders - Part 3
: soils treated with hydraulic binders possibly combined with lime)
[33 ] NF P 98-115 : Assises de chaussées - Exécution des corps de chaussées - Constituants - Composition des
mélanges et formulation - Exécution et contrôle.
(Road foundations - Construction of pavement structures - Components. Mix components and formulae Performance and control)
[34] NF P 98-160 : Revêtement de chaussée - Enduit superficiel d’usure - Spécifications.
(Wearing courses - Surface dressing - Specifications)
[35] NF P 98-200 : Essais relatifs aux chaussées - Mesure de la déflexion
(Pavement testing - Measurement of rolling load deflection).
[36] NF P 98-200-1: Essais relatifs aux chaussées. Mesure de la déflexion engendrée par une charge roulante.
Partie 1 : Définitions, moyens de mesure, valeurs caractéristiques.
(Pavement testing - Measurement of rolling load deflection - Part 1: definitions, measurements, specific
values)
– 70 –
[37] NF P 98-200-2 : Essais relatifs aux chaussées - Mesure de la déflexion engendrée par une charge roulante
- Partie 2 : Détermination de la déflexion et du rayon de courbure avec le déflectomètre Benkelman
modifié.
(Pavement testing - Measurement of rolling load deflection - Part 2: determination of deflection and curvature
values with a modified Benkelman beam).
[38]
NF P 98-200-3 : Essais relatifs aux chaussées - Mesure de la déflexion engendrée par une charge roulante
- Partie 3 : Détermination de la déflection avec le déflectographe 02
(Pavement testing. (Measurement of rolling load deflection - Part 3: determination of deflection values using a
deflectograph 02).
- Partie 4 : détermination de la déflection avec le déflectographe 03
(Pavement testing - Measurement of rolling load deflection - Part 4: determination of deflection values using a
deflectograph 03).
- Partie 5 : Détermination de la déflexion avec la déflectographe 04.
(Pavement testing - Measurement of rolling load deflection - Part 4: determination of deflection values using a
deflectograph 04).
- Partie 6 : Détermination de la déflection avec le déflectographe béton. 03
(Pavement testing. Measurement of rolling load deflection. Part 4: determination of deflection values using a
concrete deflectograph)
- Partie 7 : détermination de la déflexion et du rayon de courbure avec un curviamètre.
(Pavement tests. Measurement of rolling load deflection. Part 7 : determination of deflection and curvature
values using a curviameter).
[43] NF P 98-230-3 : Essais relatifs aux chaussées - Préparation des matériaux traités aux liants hydrauliques
ou non traités - Partie 3 : Fabrication en laboratoire de mélange de graves ou de sables pour la confection
d’éprouvettes.
(Pavement tests - Preparation of materials that are bound with hydraulic binders or unbound - Part 3 :
Laboratory manufacture of gravel or sand mixtures for use in test specimens)
[44] NF P 98-275-1 : Essais relatifs aux chaussées - Détermination du dosage en liant répandu - Partie 1 :
Essai in situ de dosage moyen et de régularité transversale.
(Pavement tests - Determination of the rate of binder spread rate - Part 1: measurement of the mean spread
rate and transverse uniformity)
[45] NF P 98-276-1 : Essais relatifs aux chaussées - Mesure du dosage en granulats d’un enduit superficiel Partie 1 : Essai à la boîte doseuse.
(Pavement tests - Measurement of chipping aggregates rate - Part 1: test using a rate box)
[46] NF P 98-276-2 : Essais relatifs aux chaussées - Mesure du dosage en granulats d’un enduit superficiel Partie 2 : Détermination de la régularité transversale.
(Pavement tests - Measurement of the proportion of aggregate in a surface dressing - Part 2 : determination of
transverse regularity).
[47] NF P 98 732-1 : Matériels de construction et d’entretien des routes - Fabrication des mélanges - Partie1 :
Centrale de malaxage pour matériaux traités aux liants hydrauliques ou non traits
(Road construction and maintenance equipment - Manufacture of mixtures and quality control - Part 1 :
mixing plants for hydraulically treated or untreated materials
[48] NF P 98-736 : Matériels de construction et d’entretien des routes - Matériel de compactage Classification.
(Road construction and maintenance equipment – Compactors - Classification).
– 71 –
[49] NF P 98-744-1 : Matériels de construction et d’entretien des routes - Calibrage et vérification des réglages
sur chantier des doseurs continus des centrales de production de matériaux - Partie 1 : Débitmètre de
bande pour courroie transporteuse.
(Road construction and maintenance equipment - Calibration and verification of the on site settings of the
continuous dosing apparatus of material production units - Part 1: belt flow meter for belt conveyor).
sur chantier, des doseurs continus des centrales de production de matériaux - Partie 2 : Doseur pondéral à
granulats.
(Road construction and maintenance equipment - On-site calibration and verification of the settings of the
continuous dosing apparatus of material production plants - Part 2: aggregate weighing dosing machine)
sur chantier, des doseurs continus des centrales de production de matériaux - Partie 3 : Doseur
volumétrique à granulats.
continuous dosing apparatus of material production plants - Part 3: volumetric aggregate dosing machine)
pulvérulent - Essai par prélèvement sur courroie.
continuous dosing apparatus of material production plants - Part 4: dry bulk weighing dosing machine -Belt
sampling test).
pulvérulent - Essai par pesée matière.
continuous dosing apparatus of material production plants - Part 5: dry bulk weighing dosing machine Substance weighing test).
[54] NF P 98-760 : Matériel de construction et d’entretien des routes - Compacteurs à pneumatiques Évaluation de la pression de contact au sol.
(Road construction and maintenance equipment - Pneumatic-tired compactors - Evaluation of the contact
pressure on the soil).
[55] NF P 98-761 : Matériels de construction et d’entretien des routes - Compacteurs - Évaluation du moment
d’excentrique.
(Road construction and maintenance plant – Compactors - Evaluation of the eccentric moment).
[56] NF P 98-772-1 : Matériels de construction et d’entretien des routes. Module d’acquisition de données
pour centrales de fabrication des mélanges granulaires - Description et spécifications fonctionnelles.
Partie 1 : Module pour la fabrication en continu.
(Road construction and maintenance equipment - Data acquisition units for granular mix manufacturing
plants - Description and functional specifications - Part 1: continuous production unit)
[57] NF EN 197-1 : Ciment - Partie 1 : Composition, spécification et critères de conformité des ciments
courants.
(Cement - Part 1: composition, specifications and conformity criteria for common cements).
[58] NF EN 459-1 : Chaux de construction - Partie 1 : Définition, spécification et critères de conformité.
(Building lime - Part 1: definitions, specifications and conformity criteria).
[59] NF EN 459-2 : Chaux de construction - Partie 2 : Essais de laboratoire.
(Building lime - Part 2 : test methods).
[60] NF EN 933-9 : Essais pour déterminer les caractéristiques géométriques des granulats - Partie 9 :
Qualification des fines. Essai au bleu de méthylène.
(Tests to determine the geometrical properties of aggregates - Part 9: Assessment of fines. Methylene blue test)
– 72 –
[61] NF EN 1097-1 : Essais pour déterminer les caractéristiques mécaniques et physiques des granulats Partie 1 : Détermination de la résistance à l’usure (micro-DEVAL).
(Tests for determining the mechanical and physical properties of aggregates - Part 1: determination of the
resistance to wear (micro-DEVAL)).
[62] NF EN 1097-2 : Essais pour déterminer les caractéristiques mécaniques et physiques des granulats Partie 2 : Méthodes pour la détermination de la résistance à la fragmentation.
(Tests for determining the mechanical and physical properties of aggregates - Part 2: methods for determining
resistance to fragmentation).
[63] NF EN 13282 : Liants hydrauliques routiers (en préparation).
(Hydraulic road binders (in preparation)).
[64] NF EN 13286-2 : Mélanges traités aux liants hydrauliques et non traités - Partie 2 : Méthode d’essai pour
la détermination en laboratoire de la masse volumique de référence et de la teneur en eau - Compactage
Proctor.
(Unbound and hydraulically bound mixtures - Part 2: laboratory test methods for determining the design
density and water content - Proctor compaction).
[65] NF EN 13286-42 : Mélanges traités et mélanges non traités aux liants hydrauliques - Partie 42 : Méthode
d’essai pour la détermination de la résistance à traction indirecte des mélanges traités aux liants
hydrauliques.
(Unbound and hydraulically bound mixtures - Part 42: test method for determining the indirect tensile
strength of hydraulically bound mixtures).
[66] NF EN 13286-45 : Mélanges traités aux liants hydrauliques et non traités - Partie 45 : Méthode d’essai
pour la détermination du délai de maniabilité des mélanges traités aux liants hydrauliques.
(Unbound and hydraulically bound mixtures - Part 45: test method for determining the workability period of
hydraulically bound mixtures).
[67] NF EN 13286-47 : Mélanges traités aux liants hydrauliques et non traités - Partie 47 : Méthodes d’essai
pour la détermination de l’indice portant Californien (CBR), de l’indice de portance immédiate (IPI) et du
gonflement.
(Unbound and hydraulically bound mixtures - Part 47 : test method for determining California bearing ratio,
immediate bearing index and linear swelling).
[68] NF EN 13286-49 : Mélanges traités aux liants hydrauliques et non traités - Partie 49 : Essai de
gonflement accéléré pour les sols traités à la chaux et / ou au liant hydraulique
(Unbound and hydraulically bound mixtures - Part 49: Accelerated swelling test for soil treated by lime
and/or hydraulic binder).
de confection par vibrocompression des éprouvettes de matériaux traités aux liants hydrauliques.
(Unbound and hydraulically bound mixtures - Part 52: method for the manufacture of test specimens of
hydraulically bound mixtures using vibrocompression).
de confection par compression axiale des éprouvettes de matériaux traités aux liants hydrauliques.
(Unbound and hydraulically bound mixtures - Part 53: methods for preparing test specimens of hydraulically
bound mixtures using axial compression).
[71] NF EN 14227-10 : Mélanges traités aux liants hydrauliques - Spécifications - Partie 10 : Sols traités au
ciment.
(Hydraulically bound mixtures - Specifications - Part 10: soils treated with cement).
[72] NF EN 14227-11 : Mélanges traités aux liants hydrauliques - Spécifications - Partie 11 : Sols traités à la
chaux.
(Hydraulically bound mixtures - Specifications - Part 11: soils treated with lime).
laitier.
(Hydraulically bound mixtures - Specifications - Part 12: soils treated with slag).
– 73 –
liant hydraulique routier.
(Hydraulically bound mixtures - Specifications - Part 13: soils treated with hydraulic road binder).
[75] NF EN 14227-14 : Mélanges traités aux liants hydrauliques - Spécifications - Partie 14 : Sols traités à la
cendre volante.
(Hydraulically bound mixtures - Specifications - Part 14 : soils treated with fly ash).
[76] XP P 18-545 : Granulats - Eléments de définitions, conformité et codification.
(Aggregates - Defining elements, conformity and coding).
Other documents
[77] Bulletin de Liaison des LPC. Traitement de sols fins en assises de chaussées : Parties 1, 2 et 3, septembreoctobre 1984.
(Bulletin de Liaison des LPC. The Treatment of Fine Soils for Pavement Base Layers: Parts 1, 2 and 3,
September-October 1984)
[78] Bulletin de Liaison des LPC. Traitement de sols fins en assises de chaussées - Parties 4 et 5, novembredécembre 1984.
(Bulletin de Liaison des LPC. The Treatment of Fine Soils for Pavement Base Layers - Parts 4 and 5,
November-December 1984).
[79] Logiciel ALIZE-Lcpc. Routes de calcul des sollicitations créées par le trafic dans les structures de
chaussées et d’aide au dimensionnement. LCPC.
(The ALIZE-LCPC software. Approaches for calculating traffic stresses in pavement structures and design
assistance.
– 74 –
6 - Annexes
6.1 - Annex A
SOIL DATA SHEET
FOR SOILS USED IN PAVEMENT BASE LAYERS
1- IDENTIFICATION AND CLASSIFICATION OF THE SOIL:
Deposit/Stockpile:
Identification of soil:
Fine soil Gravelly soil Sandy soil
Volume of deposit or stockpile v (m3) :
Date of classification :
Level
of
uniformity:
H1
H2

2- TEST RESULTS:
FINE SOILS
Clay content
VBS
% passing
IP
D(mm)=
ρd OPN
Dmax(mm)=
Max
Average m
Min
Range e
Relative range (er = 100 e/m)
2 for the extremes of clay
content
Number of tests n (9 ou 9v / 104)
SANDY SOILS
Clay content
VBS
% passing
0.08 mm
2 mm*
D (mm) =
FS
Dmax (mm) =
Max
Average m
Min
Range e
* in the case of medium or course sand
GRAVELLY SOILS
Clay content
VBS
% passing
0,08 mm
2 mm*
D (mm) =
Dmax (mm) =
LA
MDE
Max
Average m
Code according to
XP P 18-545
Min
Range e
– 75 –
6.2 - Annex B
6.2.1 - Specifications for soils used in pavement base layers
1- Uniformity of fine sandy or gravelly soils
Joint specifications
Fine soils
Dmax - Passing fraction: Li 95
D
-
Passing fraction: Li 85
Gravelly soils
Sandy soils
<= 31.5 mm
<= 8 mm
<= 20 mm
<= 6.3 mm
Fs
Ls = 50
D or E* according to
Code of the chippings in the graded
aggregate
XP P 18-545
Li
VBS
Ls
0.1
5
Fraction passing a 0.08
mm screen
2.5**
<= 40
er
Ip
0.4
Ls
20
er
<= 40
Li
35
Ls
35
*
use possible in the case of gravelly soils containing code E chippings
** if the fraction passing a 0.08 mm screen < 12 %, Ls = 1
Specifications for H1
Fine soils
Gravelly soils and Sandy soils
e, if m ≤ 15%
<= 6
e, if m > 15%
<= 8
Fraction passing a 2 mm
screen
e
<= 20
ρdOPN
er
Fraction passing a 0,08
mm screen
Specifications for H2
<= 4
Fine soils
Gravelly soils and Sandy soils
e, if m ≤ 15%
<= 8
e, if m > 15%
<= 12
Fraction passing a 2 mm
screen *
e
<= 30
ρdOPN
er
Fraction passing a 0,08
mm screen
<= 6
* in the case of gravelly, sandy or coarse soils as defined in the foreword to NF EN 14227-1
– 76 –
2- Use of soils in pavement base layers
≤ T4
T3
Roadbase layer
H2*
H1
Sub-base layer
H2*
H2*
Traffic class
T2
T1
H2*
H1
Surface
* use possible in the case of gravelly soils containing code E chippings E
6.2.2 - Economic factors
An economic analysis can show how each item contributes the total cost of a treated soil. However, the costs
may vary considerably from one construction site to another and according to the economic circumstances.
We shall therefore present an example of a breakdown of the costs of the treated soil for a construction site with
the following characteristics :
• pavement works requiring 8,000 tonnes of treated soil ;
• thickness of the layer 30 cm ;
• in-situ treatment of the materials at the site, at a rate of 1,500 tonnes per day ;
• 1.5 % of lime ;
• 7 % of hydraulic road binder.
The results are presented in Diagrams 1 and 2 which show, respectively, the contribution of each item to the
cost of the treated soil in question and the contribution of each machine to the cost of manufacture and laying of
the treated soil in question.
This analysis shows clearly the low relative cost of :
• the preliminary studies ;
• each manufacturing and laying machine ;
• surface protection ;
• checks.
It is therefore pointless to make savings on works by neglecting these items, in particular because an
examination of previous works shows that neglecting them results, in the short and medium terms, in major
deterioration in structures with treated soil pavement base layers.
Consequently, it is essential for the client and the project manager to ensure that the recommendations in this
guide are followed and that particular attention is paid to preliminary design and to external checks.
As the quality of the interface is vital for the good performance of the structure, the rules of good practice must
be strictly applied with regard to :
• keeping the surface of the material moist ;
• the absence of lamination ;
• precise levelling without the addition of thin layers ;
• the construction of an appropriate protection layer within the required amount of time.
This requires :
• the presence of all the necessary machines in good working condition ;
• the correct use of these machines by staff who have received sufficient training and precise instructions about
works of this type.
– 77 –
6.3 - Annex C
6.3.1 - The contribution of each item to the cost of the treated soil in question
Diagram 1: The contribution of each item to the cost of the treated soil in question
Graphique 1 : INCIDENCE DE CHAQUE POSTE DANS LE COÛT DU SOL TRAITÉ CONSIDÉRÉ
Contrôle
Liant chaux
Liant chaux
Etudes préalables
Liant hydraulique
Enduit de protection
Fabrication et mise en oeuvre
Enduit de protection
Etudes préalables
Fabrication et mise en
oeuvre
Liant hydraulique
Box to the right
Lime binder
Hydraulic binder
Contrôle
Manufacturing and laying
Protection layer
Preliminary studies
Checks
6.3.2 - The contribution of each piece of machinery to the cost of the treated soil in
question
Diagram 2 : The contribution of each piece of machinery to the manufacturing and laying cost of the treated soil in question
Graphique 2 : INCIDENCE DE CHAQUE ENGIN DANS LE COÛT DE LA FABRICATION ET DE LA MISE EN
OEUVRE DU SOL TRAITÉ CONSIDÉRÉ
rampe à eau
rampe à eau
compacteur P
répandeuse
rampe à eau
répandeuse
malaxeur
niveleuse
compacteur V
compacteur V
compacteur P
rampe à eau
malaxeur
niveleuse
$Box on the right
Water spray bar
Spreader
Mixer
Grader
Vibratory compactor
– 78 –
Tyred compactor
Water spray bar
6.4 - Annex D
Treated soils in pavement base layers
Conclusions of site inspections
Some thoughts about design and the construction of pavements using fine soils treated with lime
and hydraulic binders
During the drafting of this guide, site inspections were carried out in order to validate, clarify and in some cases
add to the existing rules of best practice for the use of treated soils in pavement base layers.
As the technique of soils treated with lime and hydraulic binders has been applied a great deal in Picardie and
Haute-Normandie, the investigation concentrated on sites in these regions.
Visits were therefore made to twelve sites where fine treated soils had been used, mostly silts treated with lime
and hydraulic binders (LTCC):
• in sub-base layers, and occasionally in road base layers ;
• under moderate to heavy traffic (T3 to T0) ;
• between 6 and 18 years of age, most of them between 10 and 12 years of age ;
• most of the pavements had been monitored during manufacturing and laying, with their long-term
performance being monitored once or several times on the basis of deflexion measurements, strength
measurements conducted on core samples and ovalization tests which measure in situ the deformations that
occur in pavement layers under loading.
The total length of the works was 140 km, with the individual sites measuring 0.5 at 51 km. The total observed
length was approximately 40 km.
The characteristics of each of the inspected sites are summarized in Tables 1 to 3.
The structures at these sites are as follows, with systematic presence of an LTCC capping layer :
• 5 structures entirely consisting of LTCC : road base / sub-base / capping layer (Table 1) ;
• 4 structures with a GB road base / LTCC sub-base / LTCC capping layer (Table 2) ;
• 2 structures with a GH sub-base/ LTCC road base / LTCC capping layer (Table 3).
Principal observations
The thickness of the structures entirely constructed from LTCC was generally between 60 and 90 cm, including
the capping layer. The thickness of the sub-base road base layer generally varied between 20 and 40 cm, and
was usually between 25 and 30 cm.
The surface deflections measured on these pavements are still very low : 15 to 25 1/100 mm, except at some
specific points where a value of 100 1/100 mm may occur (zones with crazing).
The GB /treated soil structures exhibit no particular defects.
The GH/treated soil structures exhibit classical transverse cracking which cannot be blamed solely on the treated
soil sub-base layer.
The structures entirely made from LTCC – sub-base, road base layers and capping layers- behave in a very
satisfactory manner, with the following observations at specific points :
• Visual appearance
– In addition to the classical transverse cracks in hydraulic pavement base layers (occurring between every 7
to 15 m), at some sites transverse cracks have been observed to ramify, with the beginning of formation of
depressions and potholes in the wheel tracks.
– 79 –
– At some sites where work has been well conducted, crazing has been observed in the wheel track nearest the
edge of the carriageway (RD 95 at Boos); the LTCC in the rest of the pavement exhibits good performance.
This crazing is likely to be due to the presence of water at the edge of the carriageway due to poor drainage
design (no ditch, pavement at TN level, narrow grass verge) ;
– At one site (RD 925 at St Valéry en Caux) some transverse ridges which seem to be due to expansion or
sliding of the layer of asphalt concrete.
• Core samples
– Core samples provide information on the “physical” state of bonding of the interfaces and lamination. The
vast majority of LTCC/LTCC interfaces are debonded in the physical sense, and in view of the general
nature of this phenomenon, it seems unlikely for it to be due to the core sampling in itself. At the BB /
LTCC interface (structures entirely made from LTCC), the BB is generally bonded to the surface dressing,
but the LTCC fractures 1 to 2 cm below. This seems to provide evidence of the quality of the bonding
achieved by embedment, but this quality is not always exploited from a mechanical point of view (see
comments on the ovalization tests below).
– The core samples also show that the LTCC layers may exhibit lamination.
– Generally, the core samples show that the performance of the materials in situ places them in classes SOIL 2
to SOIL 3 in road base layers and SOIL 1 to SOIL 2 in sub-base layers (see § 3.3.1.) It is also clearly
apparent that dispersion is considerably lower when works have been correctly carried out and correctly
monitored.
• Ovalization tests
– These show that the deformations in the LTCC are generally very small ; moreover, it appears that, even
when the LTCC/LTCC interface is physically debonded, flexural stresses are not systematically present.
This observation could justify the selected semi-bonded hypothesis. However, these layers must not be
thought of as being perfectly bonded at any stage of their life cycle.
Lessons
The LTCC structures generally have durable mechanical performance, varying from classes SOIL 1 to SOIL 3.
These are semi-rigid materials which exhibit the same type of transverse cracking as cement-bound pavement
base layers.
The observation of core samples has shown that LTCC is almost always fractured 1 to 2 cm below its interface
with the BB. The interfaces between the LTCC layers are almost always debonded.
The mechanical operation of structures consisting entirely of LTCC, on condition that the minimum rules have
been applied during laying, never correspond to the bonded interface mode, but even if the interface is
physically debonded, the real mechanical performance is unlikely to be very poor. The semi-bonded hypothesis
in the current version of the guide can probably be accepted..
It is very important for the surface layer to be waterproof in order to ensure the material retains its mechanical
performance. Consequently, the surface protection of the road base layer must be improved. Moreover, the
surface course must be thick (a minimum of 10 cm in two layers) and regularly maintained.
The constructional measures must, in particular, take account of the need to prevent water from entering the
structure (drainage ditches that are deeper than the structure or even draining edge screens) or minimize the
harmful effects of water ingress at the edge of the structure, for example by laying material over a greater width
than the cross section and waterproofing it with a surface dressing. It is also advisable to slightly increase the
gradient of verges (while still meeting safety requirements), for example to 5%.
– 80 –
5 structures made entirely from LTCC - road base layer / sub-base layer / capping layer
Works
RD 39/ RD 81
St Romain de
Colbosc
RD 925 St
Valery en Caux
RD 95
Boos
Saint Aubin
Celloville
RN 29 / RN 27
RD 25 E
Tôtes
RD 930
St
Quentin
Length in
km
4
6
3
1
0.4
Year
1996
Traffic
10 BB
25
T1
LTCC
25
for 3 km T3 LTCC
40
for the rest
LTCC
1990
1991 / 92
1989
1984
Structure
T2
T3àT2
10 BB
20 to
30 LTCC 20 to
25 LTCC 30 to
35 LTCC
12 BB
25
LTCC
40
LTCC (capping
layer/sub-base
layer.)
10 BB
30
T 0 for 3
LTCC
30
years then
LTCC
30
T3
LTCC
T2
10 BB
20
then T LTCC
25
1
LTCC
35
LTCC
Nature of treatment
Performance
according to the sub-base layer treated
in the laboratory
Sub-base layer : soil A1
1 % CaO + 7 % ROLAC 645
Road base layer : soil A1
1 % CaO + 7% ROLAC 645
After one year:
Rt = 0.85 MPa
E = 6000 MPa
Sub-base layer: soil A1
1.5 % CaO + 7% Standardized cement
Not available
Road base layer: soil A1
1.5 % CaO + 7 % Standardized cement
Silts A1-A2
Not available
Not available
Performance measured on core samples
After 2 years
Value pair Rt – E
equivalent to the performance of Soil 2
After 4 years and 9 years:
Value pair Rt – E
Reduction in performance measured on core samples
between 3 and 7 years,
but remains equivalent to the performance of Soil 2
(value pair Rt – E)
Poor performance after 6 and 9 years
Road base layer: soil A1
Sub-base layer: boundary between soils A1 and A2
1.5 % CaO + 7 % Cem III (ex CLK)
Road base layer : soil A1, boundary with A2
1.5 % CaO + 7 % Cem III (ex CLK)
After one year:
Rt = 0.63 MPa
E = 6200 MPa
(specimens moulded at 95 % of
OPN Ds)
After 16 years:
Sub-base layer:
Rt = 0.28 MPa
E = 2600
Road base layer:
Rt = 0.49 MPa
E = 3800 MPa
Table 1: Summary of the characteristics of inspected works (structures made entirely from LTCC)
– 81 –
5 structures with an GB road base / LTCC sub-base layer / LTCC capping layer
Works
Length in
km
Year
Traffic
Structure
Nature of treatment
Performance
in the laboratory
After 1 month:
RD 29
Oisemont
2
1995
T2
4 BB
12 GB
30 LTCC
35 LTCC
After 90 days:
Rt = 0.14 MPa
Rt = 0.36 MPa
E = 2400 MPa
1 % CaO + 8 % PRV A
E = 2500 MPa
After 5 years:
(100 % de Ds opm)
Rt = 0.45 MPa
E = 3800 MPa
RN 27 Tôtes
bypass
12 BB
4
1990/91
T1
13 GB
25 LTCC
40 LTCC
7.5 BB
A 29
Yvetôt St Saëns
RN 1031
Compiègne
33
1997/98
T1
1991
T0
Rt = 0.9 MPa
E = 6000 MPa
After 3 years:
Rt = 0.68 MPa
E = 4400 MPa
(mean values)
12 GB
35 LTCC
subformation 35
LTCC
8 BB
7
2 % CaO + 7 % standardized cement
After one year:
15 GB
32 soil A
1treated 35 LTCC
Capping layer/Sub-base layer: soil A1
1% CaO + 6% ROC-AS
Sub-base layer: pre-screening at quarry A1
6 % Cem III (formerly CLK)
HOLCIM Study
After 90 days:
Rt = 0.52 MPa
E = 6900 MPa
SCETAUROUTE
Documents
Tests on core samples
After 90 days:
Rt = 0.38 MPa
E = 10700 MPa
Table n° 2: Summary of the characteristics of inspected works (structures with a GB road base layer, an LTCC sub-base layer and an LTCC capping layer)
– 82 –
2 structures with a bound graded aggregate road base layer / LTCC Sub-base layer LTCC / LTCC capping layer
Works
Length in km
Year
Traffic
Structure
Nature of treatment
Performance
in the laboratory
After one year:
8 BB
RD 930
Nesle
8
1988/89
T1
30 GTLH 25
LTCC
Rt = 0.68 MPa
1 % CaO + 7 % Cem III (ex CLK)
E = 3500 MPa
35 LTCC
RN 27
Tôtes Manéhouville
16
1995/96
T1
10 BB
23 GCV
25 LTCC
35
LTCC
(100 % of OPN Ds)
1 % CaO + 7 % Cem II 32.5
After 90 days:
Rt = 0.49 MPa
After 12 years:
Rt = 0.86 MPa
E = 6000 MPa
After one year:
Rt = 0.83 MPa
No information
E = 3600 MPa
Table n° 3: Summary of the characteristics of inspected works (Structures with a GH road base layer, an LTCC sub-base layer and an LTCC capping layer)
– 83 –
– 84 –
This guide codifies the technique of soil treatment with hydraulic
binders, in some cases in combination with lime, for the construction
of pavement base layers. It supplements the “Guide technique
Traitement des sols à la chaux et/ou aux liants hydrauliques Terrassement et couche de forme” (GTS – Sétra/LCPC, 2000) and the
applicable standards.
The first part of the document explains the types of soils involved and
the specifications for uniformity. It details the content of studies and
how they change in nature from geological surveys to laboratory tests.
The second part describes the design of treated soil pavement base
layers. It states the traffic classes for which these materials may be
used and explains, with regard to the design method, the parameters
that are specific to treated soils, in particular the mechanical
characteristics measured in a laboratory weighted on the basis of the
conditions at the site and the state of the interface. It ends with
examples of design using fine treated soils.
The third part explains how works and the monitoring of the materials
should be performed, the ways the materials should be prepared at the
construction site, defines the levels of quality on the basis of the
equipment used (in-situ and in a plant), the conditions of transport and
laying, the surface protection to be applied on the basis of forecast
stresses and the quality control procedures.
This document ends with a series of annexes dealing with the soil data
sheet and the specifications of soils used in pavement base layers,
some economic factors and, finally, a summary of the survey that was
carried out on treated soil structures constructed in France.
Service d'études sur les transports, les routes et leurs aménagements
46, avenue Aristide Briand – BP 100 – 92225 Bagneux Cedex – France
téléphone : 33 (0)1 46 11 31 31 – télécopie : 33 (0)1 46 11 31 69
This document is available and can be downloaded on Sétra website:
http://www.setra.equipement.gouv.fr
The Sétra authorization is required for reproduction of this document (all or even part)
© 2008 Sétra - Reference: 0857w - ISRN: EQ-SETRA--08-ED34--FR+ENG
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