Unbound and hydraulically bound mixtures - Part 7: Cyclic load triaxial test for unbound mixtures

This standard specifies two methods for determining the resilient and the permanent behaviour of unbound mixtures under conditions that simulate the physical conditions and stress states of these materials in layers beneath the surface layer of a pavement subjected to moving loads. The two test methods are provided according to the maximum size of particles: - Method A: The Variable Confining Pressure (VCP) method in which the cell pressure is cycled in phase with the axial load. This method applies to unbound mixtures in which all particles pass the 31,5 mm test sieve.

Ungebundene und hydraulisch gebundene Gemische - Teil 7: Dreiaxialprüfung mit zyklischer Belastung für ungebundene Gemische

Diese Europäische Norm legt Verfahren zur Bestimmung sowohl des plastischen als auch des elastischen Spannungs-Verformungsverhaltens von Gesteinskörnungen  fest, wobei der auftretende Beanspruchungszustand (zyklische Beanspruchung) der Tragschichten ohne Bindemittel (ToB) in Straßenbefestigungen simuliert wird.  Diese Verfahren ermöglichen es,  verschiedene Gesteinskorngemische auf ihre Eignung als Tragschichtmaterial einzuschätzen sowie Eingangswerte für die ToB im Rahmen einer analytischen Bemessung von Straßenbefestigungen zu erhalten.
Diese Prüfung ist für zylindrische Probekörper aus Gesteinskörnungen anwendbar, die durch Verdichtung im Labor her-gestellt wurden (gestörte Proben) und deren  maximale  Korngröße kleiner als ein Fünftel des Probekörperdurchmessers ist.
Zwei Prüfverfahren  stehen zur Verfügung:
3 Verfahren A: Verfahren  mit variablem Zelldruck  (Variable Con-fining Pressure, VCP), bei dem der Zelldruck zyklisch und in Phase mit der Axialspannung aufgebracht wird.
3 Verfahren B: Verfahren mit  konstantem Zelldruck (Constant Con-fining Pressure, CCP), bei dem nur die Axialspannung zyklisch und der Zelldruck konstant aufgebracht werden.

Mélanges avec ou sans liant hydraulique - Méthodes d'essai - Partie 7: Essai triaxial sous charge cyclique pour mélanges sans liant hydraulique

La présente norme définit des méthodes d'essai permettant de déterminer le comportement réversible ou les déformations permanentes des mélanges non traités dans des conditions simulant les conditions d'état et les états de contrainte de ces matériaux dans les couches de chaussées soumises a des charges roulantes. Ces méthodes d'essai permettent de déterminer des propriétés mécaniques qui peuvent etre utilisées pour classer les matériaux suivant leurs performances mécaniques, et pour effectuer des calculs de structures de chaussées.
Ces essais sont réalisés sur des éprouvettes cylindriques de mélange non traité, préparées par compactage en laboratoire. La dimension des plus gros éléments du matériau doit etre inférieure a un cinquieme du diametre de l'éprouvette.
Pour l'application des chargements sur l'éprouvette, deux méthodes peuvent etre utilisées :
3 méthode A : Méthode a pression de confinement variable (VCP), dans laquelle la pression dans la cellule triaxiale varie de façon cyclique, en phase avec la charge axiale ;
3 méthode B : Méthode a pression de confinement constante (CCP), dans laquelle on applique un chargement axial cyclique et une pression de confinement constante.

Nevezane in hidravlično vezane zmesi – 7. del: Triosni preskus s ciklično obremenitvijo nevezanih zmesi

General Information

Status
Published
Publication Date
31-May-2004
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Jun-2004
Due Date
01-Jun-2004
Completion Date
01-Jun-2004

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.FLNOLþQRUngebundene und hydraulisch gebundene Gemische - Teil 7: Dreiaxialprüfung mit zyklischer Belastung für ungebundene GemischeMélanges avec ou sans liant hydraulique - Méthodes d'essai - Partie 7: Essai triaxial sous charge cyclique pour mélanges sans liant hydrauliqueUnbound and hydraulically bound mixtures - Part 7: Cyclic load triaxial test for unbound mixtures93.080.20Materiali za gradnjo cestRoad construction materialsICS:Ta slovenski standard je istoveten z:EN 13286-7:2004SIST EN 13286-7:2004en01-junij-2004SIST EN 13286-7:2004SLOVENSKI
STANDARD



SIST EN 13286-7:2004



EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 13286-7January 2004ICS 93.080.20English versionUnbound and hydraulically bound mixtures - Part 7: Cyclic loadtriaxial test for unbound mixturesGraves traitées aux liants hydrauliques et graves nontraitées - Partie 7: Essai triaxial sous charge cyclique pourmélanges sans liant hydrauliqueUngebundene und hydraulisch gebundene Gemische - Teil7: Dreiaxialprüfung mit zyklischer Belastung fürungebundene GemischeThis European Standard was approved by CEN on 14 November 2003.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2004 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 13286-7:2004: ESIST EN 13286-7:2004



EN 13286-7:2004 (E)2ContentsPageForeword.41Scope.62Normative references.63Symbols and abbreviations.74Principle.84.1Procedure for the study of the resilient behaviour.84.2Procedure for the study of permanent deformations.84.3Multi-stage procedure.85Apparatus.85.1General.85.2Triaxial pressure chamber (‘cell’).95.2.1General.95.2.2Chamber medium.95.2.3Top and bottom plate.95.3Loading device.95.3.1Method A – Variable confining pressure.95.3.2Method B - Constant confining pressure.95.4Pressure transducers.105.5Axial load transducer.105.6Response measuring equipment.105.7Other equipment.105.8Specimen cap and base.105.9Porous discs.105.10Semi-permeable filters.115.11Membrane.115.12Specimen-size measurement devices.115.13Balance.115.14Testing environment.116Preparation.116.1General.116.2Set up of specimen and deformation measuring equipment.127Test procedures for the study of the resilient behaviour.127.1Principle.127.2Method A: Variable confining pressure.127.2.1General.127.2.2Conditioning of the specimen.127.2.3Repeated loading for resilient testing.137.3Method B: Constant confining pressure.147.3.1General.147.3.2Conditioning of the specimen.147.3.3Repeated loading for resilient testing.158Test procedures for the study of permanent deformation.178.1Principle.178.2Single Stage loading.178.2.1General.178.2.2Method A: Variable confining pressure.178.2.3Method B : Constant confining pressure.178.3Multi-stage loading.18SIST EN 13286-7:2004



EN 13286-7:2004 (E)39Test report.199.1General.199.2General data.199.3Conditioning of the specimen.209.4Resilient behaviour.209.5Permanent behaviour (single stage or multi-stage loading).20Annex A (informative)
Measurement of specimen deformations.21A.1Measurement system using LVDTs.21A.2Measurement system using linear variable displacement transducers and rings withstrain gages.24Annex B (informative)
Preparation methods.25B.1General.25B.2Specimen conditions.25B.3Method 1 – Compaction by vibrocompression.25B.4Method 2 – Compaction by vibrating hammer.26Annex C (informative)
Guidance on test procedures and ranking of materials.28C.1Purpose.28C.2Experimental stress levels for permanent deformation tests.28C.3Ranking of materials based on resilient behaviour tests.28C.4Ranking of materials based on permanent deformation tests.29C.4.1Procedure.30C.4.2Interpretation.30C.4.3Ranking.31C.4.4Application.31Annex D (informative)
Suggested tables for presentation of test results.33Bibliography.36SIST EN 13286-7:2004



EN 13286-7:2004 (E)4ForewordThis document (EN 13286-7:2004) has been prepared by Technical Committee CEN/TC 227 “Roadmaterials”, the secretariat of which is held by DIN.This European Standard shall be given the status of a national standard, either by publication of an identicaltext or by endorsement, at the latest by July 2004, and conflicting national standards shall be withdrawn at thelatest by July 2004.Annexes A, B, C and D are informative.This European Standard is one of a series of standards as listed below.EN 13286-1, Unbound and hydraulically bound mixtures — Part 1: Test methods for laboratory referencedensity and water content — Introduction, general requirements and sampling.prEN 13286-2, Unbound and hydraulically bound mixtures — Part 2: Test method for the determination of thelaboratory reference density and water content — Proctor compaction.EN 13286-3, Unbound and hydraulically bound mixtures — Part 3: Test methods for laboratory referencedensity and water content — Vibrocompression with controlled parameters.EN 13286-4, Unbound and hydraulically bound mixtures — Part 4: Test methods for laboratory referencedensity and water content — Vibrating hammer.EN 13286-5, Unbound and hydraulically bound mixtures — Part 5: Test methods for laboratory referencedensity and water content — Vibrating table.EN 13286-7, Unbound and hydraulically bound mixtures — Test methods - Part 7: Cyclic load triaxial test forunbound mixtures.EN 13286-40, Unbound and hydraulically bound mixtures — Part 40: Test method for the determination of thedirect tensile strength of hydraulically bound mixtures.EN 13286-41, Unbound and hydraulically bound mixtures — Part 41: Test method for the determination of thecompressive strength of hydraulically bound mixtures.EN 13286-42, Unbound and hydraulically bound mixtures — Part 42: Test method for the determination of theindirect tensile strength of hydraulically bound mixtures.EN 13286-43, Unbound and hydraulically bound mixtures — Part 43: Test method for the determination of themodulus of elasticity of hydraulically bound mixtures.EN 13286-44, Unbound and hydraulically bound mixtures — Part 44: Test method for the determination of thealpha coefficient of vitrified blast furnace slag.prEN 13286-45, Unbound and hydraulically bound mixtures — Part 45: Test method for the determination ofthe workability period of hydraulically bound mixtures.EN 13286-46, Unbound and hydraulically bound mixtures — Part 46: Test method for the determination of themoisture condition value.EN 13286-47, Unbound and hydraulically bound mixtures - Part 47: Test method for the determination of theCalifornia bearing ratio, immediate bearing index and linear swelling.SIST EN 13286-7:2004



EN 13286-7:2004 (E)5prEN 13286-48, Unbound and hydraulically bound mixtures — Part 48: Test method for the determination ofthe degree of pulverisation.prEN 13286-49, Unbound and hydraulically bound mixtures — Part 49: Accelerated swelling test of soiltreated by lime and/or hydraulic binder.prEN 13286-50, Unbound and hydraulically bound mixtures — Part 50: Methods for making test specimensusing proctor equipment or vibrating table compaction.prEN 13286-51, Unbound and hydraulically bound mixtures — Part 51: Methods for making test specimens byvibrating hammer compaction.prEN 13286-52, Unbound and hydraulically bound mixtures — Methods for making test specimens - Part 52:Making specimens by vibro-compression.prEN 13286-53, Unbound and hydraulically bound mixtures — Methods for making test specimens - Part 53:Making cylindrical specimens by axial compressionAccording to the CEN/CENELEC Internal Regulations, the national standards organizations of the followingcountries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic,Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerlandand United Kingdom.SIST EN 13286-7:2004



EN 13286-7:2004 (E)61 ScopeThis European Standard specifies test procedures for determining the resilient and permanent behaviour ofunbound mixtures under conditions that simulate the physical conditions and stress states of these materialsin pavement layers subjected to moving loads. These procedures allow to determine mechanical propertiesthat can be used for performance ranking of materials and for calculating the structural responses ofpavement structures.The test is applicable to cylindrical specimens of unbound mixtures prepared by laboratory compaction, withan absolute maximum particle size smaller than one fifth of the specimen diameter.For the loading of the specimen, two methods are provided :¾ Method A: The Variable Confining Pressure method in which the cell pressure is cycled in phase with theaxial load.¾ Method B: The Constant Confining Pressure method in which only cyclic axial loading and constantconfining pressure are performed.2 Normative referencesThis European Standard incorporates by dated or undated reference, provisions from other publications.These normative references are cited at the appropriate places in the text and the publications are listedhereafter. For dated references, subsequent amendments to or revisions of any of these publications apply tothis European Standard only when incorporated in it by amendment or revision. For undated references thelatest edition of the publication referred to applies (including amendments).EN 13285, Unbound mixtures - Specification.SIST EN 13286-7:2004



EN 13286-7:2004 (E)73 Symbols and abbreviationsFor the purposes of this European Standard, the symbols and definitions in Table 1 apply.Table 1 — Symbols and definitionsSymbolDefinitionUnitwWater content%rdDry densityMg/m3NNumber of load cyclessNormal stresskPas1Total axial stress (major principal stress)kPas1min, s1maxMinimum and maximum values of s1 during one load cyclekPas1rResilient axial stress,
s1r = s1max – s1minkPas3Total radial stress; i.e. the applied confining pressure in the triaxial chamber or thevacuum inside the specimen when no triaxial chamber is used (minor andintermediate principal stress)kPas3min, s3maxMinimum and maximum values of s3 during one load cyclekPas3rResilient radial stress,
s3r = s3max – s3minkPasdDeviator stress,
sd = s1 – s3kPaL0Gauge length for axial displacement, immediately following specimen preparationmmR0Gauge length for radial displacement, immediately following specimen preparationmmLp(N)Permanent axial displacement at cycle N, defined as the displacementaccumulated during the application of a single stress combination, from thebeginning of the first cycle to the end of cycle NmmRp(N)Permanent radial displacement at cycle N, defined as the displacementaccumulated during the application of a single stress combination, from thebeginning of the first cycle to the end of cycle NmmLr(N)Resilient axial displacement at cycle N, defined as the displacement during theunloading part of the cycle (between the point where the applied stresses aremaximum and the end of the cycle)mmRr(N)Resilient radial displacement at cycle N, defined as the displacement during theunloading part of the cyclemme1rResilient or recovered axial strain. At cycle N,
e1r (N)= Lr(N)/ L010–3e1pPermanent axial strain. At cycle N , e1p(N)= Lp(N)/ L010–3e3rResilient or recovered radial strain.At cycle N,
e3r (N)= Rr(N)/ R010–3e3pPermanent radial strain. At cycle N,
e3p (N)= Rp(N)/ R010–3ErResilient modulus,
rrrrrr1rrrrr3313133112222esesesssss-+-+=EWhen s3r = 0, (constant confining pressure) : rrr11es=EMPaNOTECompressive stresses and strains are positive.SIST EN 13286-7:2004



EN 13286-7:2004 (E)84 PrincipleThe cyclic triaxial test consists of imposing, on a cylindrical specimen of unbound granular material, cyclicstresses that reproduce the stress range in an unbound pavement layer, and in measuring the axial and radialstrains of the specimen induced by this loading. In method A (Variable Confining Pressure), a cyclic axialdeviator stress and a variable (cyclic) confining cell pressure, varying in phase, are applied. A simplified stressregime with a cyclic axial deviator stress and a constant confining pressure may also be adopted, method B.The standard proposes three different test procedures, described below.4.1 Procedure for the study of the resilient behaviourThe resilient behaviour of the material represents the behaviour during one load application. The results of thetest can be used to determine values of the elastic modulus of the material for different stress levels, orparameters of non linear elastic models which can be used in analytical and numerical pavement designprocedures.In this procedure, a cyclic conditioning is first applied to stabilise the permanent strains of the material andattain a resilient behaviour. This conditioning is performed by applying a large number of cycles of a stresspath that corresponds to the maximum stress level applied during the test. The resilient behaviour is thenobserved for several stress paths applied each one with a small number of cycles on the same specimen.4.2 Procedure for the study of permanent deformationsEach permanent deformation test consists in applying a large number of load cycles of a single stresscombination, without prior conditioning. This procedure can be used to determine permanent deformations ofthe material for a particular stress level, or parameters of models of prediction of permanent deformations,which can be used for pavement analysis and design.4.3 Multi-stage procedureThis procedure can be used for a rapid evaluation of permanent deformations produced by different stresslevels. It consists of applying several load sequences, with increasing stress levels, to the same specimen,until the cumulated permanent axial deformation exceeds a specified limit.5 Apparatus5.1 GeneralThe test apparatus shall be able to apply the required cyclic loading to a cylindrical specimen with a diameterlarger than 5 times the maximum particle size of the material, and a height twice the diameter (±2 %).In test method A, the apparatus shall be able to cycle the cell pressure in phase with the axial load. Hence, atriaxial cell shall be used.In test method B, only the axial load is cyclic, and the confining pressure is held constant. Hence, the triaxialcell may not be necessary, and the constant confining pressure may be applied by partial vacuum inside thespecimen.NOTEUsing a system without a triaxial cell will prevent applying some of the additional stress paths in this standardthat are considered important for some types of structures.SIST EN 13286-7:2004



EN 13286-7:2004 (E)95.2 Triaxial pressure chamber (‘cell’)5.2.1 GeneralThe pressure chamber, or ‘cell’, is similar to most conventional triaxial cells except that it is somewhat largerto facilitate the internally mounted load and deformation measuring equipment, and has additional outlets forthe electrical leads from the measuring devices.5.2.2 Chamber mediumWater, air, silicon oil or other suitable medium may be used as the chamber medium. Water is not suitable ifthe instrumentation does not have fully sealed electrical connections.5.2.3 Top and bottom plateTop and bottom plate alignment is critical to maintain uniform stresses and strains in the specimen. A ball jointmay be suitable for alignment.5.3 Loading device5.3.1 Method A – Variable confining pressureFor test procedures with variable confining pressure (described in 7.2 and 8.2.2) the loading device shallsatisfy the following requirements:¾ The loading device shall be capable of applying variable repeated axial loads and confining pressures, infixed cycles of load and release.¾ During loading, the axial load and the confining pressure shall remain proportional and vary in phase.¾ The axial loading device shall be able to apply a maximum deviatoric stress of 600 kPa on the specimen,and the cyclic pressure control system shall be able to apply a maximum confining pressure of 300 kPa.¾ During each cycle, the minimum and maximum values of deviatoric stress and confining pressure shall beapplied with an accuracy of ±2 kPa or 1 %, whichever is the greater.¾ The frequency of loading shall be maintained between 0,2 Hz and 10 Hz.¾ The phase difference between the pulses of the axial load and of the confining pressure shall not exceed1 % of the cycle duration.5.3.2 Method B - Constant confining pressureFor test procedures with constant confining pressure (described in 7.3, 8.2.3 and 8.3), the loading device shallsatisfy the following requirements:¾ The axial loading device shall be able to apply variable repeated axial loads, in fixed cycles of load andrelease, and to apply a maximum deviatoric stress of 600 kPa on the specimen.¾ The pressure control system shall be able to apply a maximum confining pressure of at least 70 kPa.¾ The confining pressure may also be applied by partial vacuum inside the specimen.¾ During each cycle, the minimum and maximum values of deviatoric stress and the constant confiningpressure shall be applied with an accuracy of ±2 kPa or 1 %, whichever is the greater.SIST EN 13286-7:2004



EN 13286-7:2004 (E)10¾ The frequency of axial loading shall be maintained between 0,2 Hz and 10 Hz.5.4 Pressure transducersThe confining pressures in the cell or the partial vacuum in the specimen shall be monitored by pressuretransducers with suitable sensitivity ranges, and with an accuracy of ±2 kPa.5.5 Axial load transducerThe axial load applied to the specimen shall be monitored by a transducer with a suitable sensitivity rangewhich will yield measurements of axial stress to an accuracy of ±2 kPa. The load transducer shall preferablybe placed inside the triaxial cell, in direct contact with the specimen cap.5.6 Response measuring equipmentThe axial deformations of the specimen shall be measured using at least two displacement transducersattached directly to the central part of the specimen (such that the gauge length does not exceed half of theheight of the specimen). An appropriate system for measuring axial deformations, using three linear variabledisplacement is presented in annex A.The radial deformations of the specimen shall be measured at mid-height of the specimen, using transducersattached directly to the specimen. An appropriate system for measuring radial deformations, using three linearvariable displacement is presented in annex A.The axial and radial strains shall be measured with an accuracy of 5 ´ 10–3 mm + 10–3 ´ L
(where L is themeasured displacement in millimetre).Readings of all transducers should be recorded separately.5.7 Other equipmentIt is necessary to provide suitable signal excitation, conditioning, and recording equipment in addition to themeasuring devices for simultaneous recording of axial load, confining pressure and axial and radialdeformations.The recording system shall operate at a frequency, or be of a type, which is able to capture both the minimumand the maximum values of stress applied and strain incurred at the frequency of testing which is to beemployed.5.8 Specimen cap and baseThe specimen cap and base shall be designed to provide drainage from both ends of the specimen. Theyshall be constructed of a rigid, non-corrosive, impermeable material, and each shall, except for the drainageprovision, have a circular plane surface in contact with the porous discs of circular cross section. The diameterof the cap and base shall be equal to or larger than the initial diameter of the specimen. The specimen baseshall be connected to the triaxial compression chamber to prevent lateral motion or tilting, and the specimencap shall be designed such that eccentricity of the loading piston-to-cap contact relative to the vertical axis ofthe specimen does not exceed 1 % of the specimen’s diameter. The cylindrical surface of the specimen baseand cap that contacts the membrane to form a seal shall be smooth and free of scratches.5.9 Porous discsThe specimen shall be separated from the specimen cap and base by rigid porous discs fastened to thespecimen cap and base of a diameter equal to or a little smaller than that of the specimen. The discs shall beregularly checked by passing air or water under pressure through them to determine whether they haveSIST EN 13286-7:2004



EN 13286-7:2004 (E)11become clogged. If found to be clogged, new porous discs should be used to ensure effective drainage of thespecimen at the cap and base.5.10 Semi-permeable filtersWhen performing constant moisture tests in which the moisture/suction regime is controlled, it is necessary touse semi-permeable filters. These shall be both waterproof and air permeable. They shall be placed betweenthe specimen and cap and between the specimen and b
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