BS EN 12697-25 (2005) Bituminous Mixtures Test Methods For Hot Mix Asphalt PDF
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BRITISH STANDARD
I S B ) c ( , y p C o d e l l o r t n o c n U , 9 2 : 3 1 0 1 0 2 / 8 0 / 1 3 , y b r e D f o y t i s r e v i n U , x x . r M : y p o C d e s n e c i L
Bituminous mixtures — Test methods mix asphalt —for hot Part 25: Cyclic compression test
The European Standard EN 12697-25:2005 has the status of a Britis Bri tish h Standar Standard d
ICS 93.080.20
BS EN 12697-25:2005
BS EN 12697-25:2005
National foreword I S B ) c ( , y p
This British Standard is the official English language version of EN 12697-25:2005. 12697-25:2005. The UK participation in its preparation was entrusted by Technical T echnical Committee B/510, Road materials, to Subcommittee B/510/1, Coated macadam and hot asphalt, which has the responsibility to:
C o d e l l o r t n o c n U , 9 2 : 3 1 0 1 0 2 / 8 0 / 1 3 , y b r e D f o y t i s r e v i n U This British Standard was , published under the authority x of the Standards Policy and x Strategy Committee on May 20 2005 05 . 4 May r M : y p o C d e s © BSI May y 2005 2005 n BSI 4 Ma e c i L
ISBN 0 580 45985 5
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aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed;
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monitor related international and European developments and promulgate them in the UK.
A list of organizations represented on this subcommittee can be obtained obta ined on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI the BSI Catalogue Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI the BSI Electronic Catalogue or Catalogue or of British Briti sh Standards Standards Onl Online. ine. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations.
Summary of pages This document comprises a front cover, an inside in side front cover, the EN title page, pages 2 to 29 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued.
Amendments issued since publication publication Amd. No.
Date
Comments
I S B ) c ( , y p C o d e l l o r t n o c n U , 9 2 : 3 1 0 1 0 2 / 8 0 / 1 3 , y b r e D f o y t i s r e v i n U , x x . r M : y p o C d e s n e c i L
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 12697-25 April 2005
ICS 93.080.20
English version
Bituminous mixtures - Test methods for hot mix asphalt - Part 25: Cyclic compression test Mélanges bitumineux - Méthodes d'essai pour mélange hydrocarboné à chaud - Partie 25 : Essai cyclique de compression
Asphalt - Prüfverfahren für Heißasphalt - Teil 25: Druckschwellversuch
This European Standard was approved by CEN on 15 March 2005. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standardofexists in member three official (English,and French, German). A version in any other under the responsibility a CEN into versions its own language notified to the Central Secretariat haslanguage the samemade statusby astranslation the official versions. 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 STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36
© 2005 CEN
All rights of exploitatio exploitationn in any form and by any means reserved reserved worldwide for CEN national Members.
B-1050 Brussels Brussels
Ref. No. EN 12697-25:2005: E
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EN 12697-25:2005 (E)
Contents
page
Foreword .......................... ........................................ ........................... ........................... ............................ ........................... ........................... ......................... ......................... ............................ .....................3 .......3 Introduction.......................... Introduction............. ........................... ........................... ........................... ........................... ........................... ........................... ....................... ........................ ........................... ...................6 ......6 1
Scope ............. .......................... ........................... ............................ ........................... ........................... ............................ ............................ ........................... .......................... .........................7 ............7
2
Normative references ............ .......................... ........................... .......................... ........................... ........................... .......................... ........................... .......................... ...............7 ...7
3
Terms and definitions.............. definitions............................ ........................... .......................... ........................... .......................... .......................... .......................... .......................... ...............7 .7
4
Test method A — Uniaxial cyclic compression test with confinement........................ confinement.................................... ...................9 .......9
4.1
Principle........................ Principle........... ........................... ........................... ........................... ........................... ........................... ............................ .......................... ......................... .........................9 ............9
4.2
Apparatus ............ ......................... ........................... ........................... ........................... ........................... ........................... ........................... ......................... ........................ ....................10 ........10
4.3
Specimen preparation ............. .......................... ........................... .......................... ........................... ........................... .......................... ........................... ....................... ............13 ..13
4.4
Conditioning Conditionin g ............ ......................... ........................... ........................... ........................... ........................... ........................... ........................... ....................... ........................ ..................14 ....14
4.5
Test procedure ............ ......................... ........................... ........................... ......................... ........................... ........................... ......................... ....................... ........................ ................14 ..14
4.6
Calculation Calculatio n and expression of results............ results......................... .......................... ......................... ......................... .......................... ........................... .................15 ...15
4.7
Test report ............. ......................... .......................... ........................... ........................... ........................... ........................... ........................... ....................... ....................... .....................16 ........16
4.8 5
Precision....................................... Precision.......................... ........................... ............................ ........................... ........................... .......................... ........................ .......................... ......................16 ........16 Test method B — Triaxial cyclic compression test ............ ........................ ......................... .......................... ......................... ......................17 ..........17
5.1
Principle........................ Principle........... ........................... ........................... ........................... ........................... ........................... ............................ .......................... ......................... .......................17 ..........17
5.2
Apparatus ............ ......................... ........................... ........................... ........................... ........................... ........................... ........................... ......................... ........................ ....................19 ........19
5.3
Specimen preparation ............. .......................... ........................... .......................... ........................... ........................... .......................... ........................... ....................... ............22 ..22
5.4
Conditioning Conditionin g ............ ......................... ........................... ........................... ........................... ........................... ........................... ........................... ....................... ........................ ..................23 ....23
5.5
Test procedure ............ ......................... ........................... ........................... ......................... ........................... ........................... ......................... ....................... ........................ ................24 ..24
5.6
Calculation Calculatio n and expression of results............ results......................... .......................... ......................... ......................... .......................... ........................... .................25 ...25
5.7
Test report ............. ......................... .......................... ........................... ........................... ........................... ........................... ........................... ....................... ....................... .....................27 ........27
5.8
Precision.......................... Precision............ ........................... ........................... ............................ ........................... ........................... .......................... ........................ .......................... ......................28 ........28
Bibliography....................... Bibliograph y..................................... .......................... .......................... ........................... .......................... ........................... .......................... ......................... ........................... ...................29 .....29
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EN 12697-25:2005 (E)
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Foreword This document (EN 12697-25:2005) has been prepared by Technical Committee CEN/TC 227 “Road materials”, 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 identical text or by endorsement, at the latest by October 2005, and conflicting national standards shall be withdrawn at the latest by October 2005. This European Standard is one of a series of standards as listed below: EN 12697-1, Bituminous mixtures — Test methods for hot mix asphalt — Part 1: Soluble binder content. EN 12697-2, Bituminous mixtures - Test method for hot mix asphalt - Part 2: Determination of particle size distribution. EN 12697-3, Bituminous mixtures - Test methods for hot mix asphalt - Part 3: Bitumen recovery: Rotary evaporator. EN 12697-4, Bituminous mixtures - Test methods for hot mix asphalt - Part 4: Bitumen recovery: Fractionating column. EN 12697-5, Bituminous mixtures — Test methods ffor or hot mix as asphalt phalt — Part 5: Deter Determination mination of the maximum density. EN 12697-6, Bituminous mixtures — Test methods for hot mix asphalt — Part 6: Determination of bulk density of bituminous specimens. EN 12697-7, Bituminous mixtures — Test methods for hot mix asphalt — Part 7: Determination of bulk density of bituminous specimens by gamma rays. EN 12697-8, Bituminous mixtures - Test methods for hot mix asphalt - Part 8: Determination of void characteristics of bituminou bituminous s specimens. EN 12697-9, Bituminous mixtures — Test methods ffor or hot mix as asphalt phalt — Part 9: Deter Determination mination of the reference density. EN 12697-10, Bituminous mixtures — Test methods for hot mix asphalt — Part 10: Compactability. EN 12697-11, Bituminous mixtures - Test methods for hot mix asphalt - Part 11: Determination of the affinity between aggregate and bitumen. EN 12697-12, Bituminous mixtures - Test methods for hot mix asphalt - Part 12: Determination of the water sensitivity of bituminous specimens. EN 12697-13, Bituminous mixtures — Test methods for hot mix asphalt — Part 13: Temperature measurement. EN 12697-14, Bituminous mixtures — Test methods for hot mix asphalt — Part 14: Water content. EN 12697-15, Bituminous mixtures - Test methods for hot mix asphalt - Part 15: Determination of the segregation sensitivity. EN 12697-16, Bituminous mixtures — Test methods for hot mix asphalt — Part 16: Abrasion by studded tyres.
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EN 12697-25:2005 (E)
EN 12697-17, Bituminous mixtures - Test methods for hot mix asphalt - Part 17: Particle loss of porous asphalt specimen. EN 12697-18, Bituminous mixtures — Test methods for hot mix asphalt — Part 18: Binder drainage.
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EN 12697-19, Bituminous mixtures — Test methods for hot mix asphalt — Part 19: Permeability of specimen. EN 12697-20, Bituminous mixtures — Test methods for hot mix asphalt — Part 20: Indentation using cube or Marshall specimens. EN 12697-21, Bituminous mixtures — Test methods for hot mix asphalt — Part 21: Indentation using plate specimens. EN 12697-22, Bituminous mixtures — Test methods for hot mix asphalt — Part 22: Wheel tracking. EN 12697-23, Bituminous mixtures - Test methods for hot mix asphalt - Part 23: Determination of the indirect tensile strength of bituminous specimens. EN 12697-24, Bituminous mixtures — Test methods for hot mix asphalt — Part 24: Resistance to fatigue. EN 12697-25, Bituminous mixtures — Test methods for hot mix asphalt — Part 25: Cyclic compression test. EN 12697-26, Bituminous mixtures — Test methods for hot mix asphalt — Part 26: Stiffness. EN 12697-27, Bituminous mixtures — Test methods for hot mix asphalt — Part 27: Sampling. EN 12697-28, Bituminous mixtures — Test methods for hot mix asphalt — Part 28: Preparation of samples for determining binder content, water content and grading. EN 12697-29, Bituminous mixtures — Test methods for hot mix asphalt — Part 29: Determination of the dimensions of a bituminous specimen. EN 12697-30, Bituminous mixtures - Test methods for hot mix asphalt - Part 30: Specimen preparation by impact compactor. EN 12697-31, Bituminous mixtures - Test methods for hot mix asphalt - Part 31: Specimen preparation by gyratory compactor. EN 12697-32, Bituminous mixtures — Test methods for hot mix asphalt — Part 32: Laboratory compaction of bituminous mixtures by vibratory compactor. EN 12697-33, Bituminous mixtures - Test methods for hot mix asphalt - Part 33: Specimen prepared by roller compactor. EN 12697-34, Bituminous mixtures — Test methods for hot mix asphalt — Part 34: Marshall test. EN 12697-35, Bituminous mixtures — Test methods for hot mix asphalt — Part 35: Laboratory mixing. EN 12697-36, Bituminous mixtures - Test methods for hot mix asphalt - Part 36: Determination of the thickness of a bituminous pavement. EN 12697-37, Bituminous mixtures - Test methods for hot mix asphalt - Part 37: Hot sand test for the adhesivity of binder on precoated chippings for HRA. EN 12697-38, Bituminous mixtures — Test methods for hot mix asphalt — Part 38: Common equipment and calibration. EN 12697-39, Bituminous mixtures — Test methods for hot mix asphalt — Part 39: Binder content by ignition.
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EN 12697-25:2005 (E)
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prEN 12697-40, Bituminous mixtures — Test methods for hot mix asphalt — Part 40: In-situ drainability. prEN 12697-41, Bituminous mixtures — Test methods for hot mix asphalt — Part 41: Resistance to de-icing fluids. prEN 12697-42, Bituminous mixtures — Test methods ffor or hot mix aspha asphalt lt — Part 42: Amount of foreign foreig n matters in reclaimed asphalt. prEN 12697-43, Bituminous mixtures — Test methods for hot mix asphalt — Part 43: Resistance to fuel. No existing European Standard is superseded.
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According to t o the CEN/CENE CEN/CENELEC LEC Internal Regulations, the national standards organizations of the following countries 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, Switzerland and United Kingdom.
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EN 12697-25:2005 (E)
Introduction This European Standard contains two test methods to determine the resistance to permanent deformation of a bituminous mixture by cyclic compression tests with confinement. The tests make it possible to rank various mixes or to check on the acceptability of a given mix. They do not allow making a quantitative prediction of rutting in the field to be made. The choice for confinement was made in order to obtain realistic test results for gap-graded mixes.
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EN 12697-25:2005 (E)
1
Scope
This European Standard describes two test methods (A and B) for determining the resistance of bituminous mixtures to permanent deformation. Test method A describes the method for determining the creep characteristics of bituminous mixtures by means of an uniaxial cyclic compression test with some confinement present. In this test a cylindrical specimen is subjected to a cyclic axial stress. To achieve a certain confinement, the diameter of the loading platen is taken smaller than that of the sample. NOTE 1
Confinement of the sample is necessary to predict realistic rutting behaviour, especially for gap-graded mixes with a large
stone fraction.
Test method B describes the method for determining the creep characteristics of bituminous mixtures by means of the triaxial cyclic compression test. In this test a cylindrical specimen is subjected to a confining stress and a cyclic axial stress. This test is most often used for the purpose of evaluation and development of new types of mixtures. This European Standard applies to specimens prepared in the laboratory or cored from the road. The maximum size of the aggregates is 32 mm. NOTE 2
For purposes purposes of compliance with with EN 13108, the test conditions a are re given in pr prEN EN 1 13108-20. 3108-20.
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Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 12697-6, Bituminous mixtures - Test methods for hot mix asphalt - Part 6: Determination of bulk density of bituminous specimens. specimens. EN 12697-27, Bituminous mixtures — Test methods for hot mix asphalt — Part 27: Sampling. EN 12697-29, Bituminous mixtures — Test methods for hot mix asphalt — Part 29: Determination of the dimensions of a bituminous specimen. specimen. EN 12697-30, Bituminous mixtures — Test methods for hot mix asphalt — Part 30: Specimen preparation by impact compactor. compactor. EN 12697-31, Bituminous mixtures — Test methods for hot mix asphalt — Part 31: Specimen preparation by gyratory compactor. compactor. EN 12697-33, Bituminous mixtures - Test methods for hot mix asphalt - Part 33: Specimen prepared by roller compactor.
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Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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EN 12697-25:2005 (E)
3.1 accuracy class permissible measuring measuring error, expressed as a percentage, in the output signal of a transducer t ransducer 3.2 contact area that portion of the pressure platen that is in contact with the test specimen 3.3 creep curve display of the cumulative axial strain, expressed in %, of the specimen as a function of the number of load applications NOTE
Generally the following stages can be distinguished (see Figure 1)
stage 1: the (initial) part of the deformation curve, where the slope of the curve decreases with increasing number of loading cycles;
stage 2: the (middle) part of the deformation curve, where the slope of the curve is quasi constant and with a turning point in the deformation curve;
stage 3: the (last) part of the deformation curve, where the slope increases with increasing number of loading cycles.
Depending on the testing conditions and on the mix, one or more stages may be absent.
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Key Key
ε N
n
Cumulative axial strain
1
Stage 1
Number of load repetitions
2
Stage 2
3
Stage 3
4
Turning point
Figure 1 — Example of a creep curve 3.4 precision the closeness of agreement between independent test results obtained under stipulated conditions NOTE 1
Precision depends only on the distribution of random errors and does not relate to th the e true va value lue or the
specified value. NOTE 2 The measure of precision is usually expressed in terms of imprecision an and d computed as a standard deviation of the test results. Less precision is reflected by a larger standard deviation.
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EN 12697-25:2005 (E)
NOTE 3 “Independent test results” means results obtained in a manner n not ot influenced by any previous result on the same or similar test object. Quantitative measures of precision depend critically on the stipulated conditions. Repeatability and reproducibility conditions are particular sets of extreme conditions.
3.5 repeatability precision under repeatability conditions 3.6 repeatability conditions conditions where independent test results are obtained with the same method on identical test items in the same laboratory by the same operator using the same equipment within short intervals of time 3.7 repeatability limit the value less than or equal to which the absolute difference between two test results obtained under repeatability conditions conditions may be expected to be within probability of 95 % NOTE
The symbol used is r .
3.8 reproducibility precision under reproducibili r eproducibility ty conditions 3.9 reproducibility conditions conditions where test results are obtained with the same method on identical test items in different laboratories with different operators using different equipment 3.10 reproducibility limit the value less than or equal to which the absolute difference between two test results obtained under reproducibility conditions conditions may be expected to be with a probability of 95 % NOTE
The symbol used is R.
3.11 single test result the value obtained by applying the standard test method fully, once to a single specimen; it may be the mean
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of two or more observations or the result of a calculation from a set of observations as specified by the standardized test method 3.12 measuring error difference between the true value of the physical quantity and the value indicated on the measuring instrument, expressed as a percentage of the true value 3.13 permanent deformation cumulative axial deformation of the specimen after a given number of load applications
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Test method A — Uniaxial cyclic compression test with confinement confinement
4.1
L
Principle
This test method determines the resistance to permanent deformation of a cylindrical specimen of bituminous mixture by repeated load. The specimens may be either prepared in the laboratory or be cored from a pavement.
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EN 12697-25:2005 (E)
A cylindrical test specimen with a diameter of 150 mm, maintained at elevated conditionin c onditioning g temperature, is placed between two t wo plan parallel loading plate platens. ns. The upper platen has a diameter diamet er of 100 mm (by an inclination inclinatio n the pressure area against the specimen has a real diameter of 96 mm). A schematic representation of the test device is given in Figure 2. The specimen is subjected to a cyclic axial block-pulse pressure, as represented in Figure 3. There is no additional lateral confinement pressure applied. During the test the change in height of the specimen is measured at specified numbers of load applications. From this, the cumulative axial strain ε N (permanent deformation) of the test specimen is determined as a function of the number of load applications. The results are represented in a creep curve as given in Figure 3. From this, the creep characteristics of the specimen are computed. The test does not allow a quantitative prediction of the rutting. Nevertheless, the test makes it possible to rank various mixes or to check on the acceptability of a given mix.
Figure 2 — Test apparatus
4.2
Apparatus
4.2.1 4.2.1.1
Test system Compression apparatus
A suitable test apparatus apparatus to generate a square (see Fi Figure gure 3 and Figure 4) and pe periodical riodical loadin loading g pulse, with a frequency of 0,5 Hz and a load of (100 ± 2) kPa. The load cell shall have a capacity of at least 2 000 N. All components shall be constructed out of corrosion-resistant steel.
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EN 12697-25:2005 (E)
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Key 1
Strain, microstrain
t
Time
2
Stress, kPa
A
Strain at preload, microstrain
3
Preload
ε iirr rr
Irreversible strain (permanent deformation)
Figure 3 — Stress and strain curve
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Key 1
Load
2
Duration of the pulse x1 + x2 + x3 + x4 < 20 % of the whole pulse
Figure 4 — Loading curve
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EN 12697-25:2005 (E)
4.2.1.2
Loading configuration
The lower platen shall have an area that stretches at least 5 mm outside the specimen. The dimensions of the upper platen shall be as follows: diameter (100 ± 0,5) mm, thickness (25 ± 0,5) mm and mass (1,55 ± 0,05) kg. The platen shall at the lower edge have an inclination as shown in Figure 5, which gives a loading circular surface with a diameter of (96 ± 1) mm. The upper platen shall be fitted with hemispherical self-aligning seating while the lower platen shall be fixed or held in place by e.g. a spigot/slot system. Both the bottom surface (the lower platen) and the upper platen shall be made from hardened corrosion-resistant steel with a polished (flat and smooth) surface. NOTE
The inclination of the lower edge can also be rounded off.
Figure 5 — Lower edge of the platen 4.2.1.3
Control and measuring system
(PC and software) for controlling, reading and collecting necessary data. The control system shall guarantee that during the test the t he physical parameter to be controlled (force) shows no oscillations. NOTE It is recommended that the control system should include a programmable function generator and a control circuit with which the desired loading signal can be generated.
4.2.1.4
Displacement transducer transducers s
The deformation measurement system shall include two displacement transducers for measuring and recording the cumulative axial deformation to the test specimen, by measuring the change in distance between the loading platens throughout the test. The transducers shall conform to accuracy class 0,2. The measuring range of the transducers shall be 5 mm at least. 4.2.1.5
Thermostati Thermostatic c chamber
A thermostatic chamber to maintain the sample at the specified test temperature. The accuracy of the temperature control shall be ±1 °C or higher. NOTE It is recommended that a sufficiently large thermostatic chamber should be chosen, so that during the test additional test specimens can be acclimatised inside the thermostatic chamber c hamber
4.2.2
Measuring instruments and accessories needed
4.2.2.1 Balance and other equipment required to determine the bulk density in accordance with EN 12697-6.
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EN 12697-25:2005 (E)
4.2.2.2 Vernier callipers or other suitable apparatus to determine the specimen dimensions in accordance with EN 12697-29. 4.2.2.3 4.2.2.3
Drying cabinet or room, temperature between 15 °C and 25 °C.
4.2.2.4 4.2.2.4
Storage area, temperature between 5 °C and 25 °C.
4.2.2.5 Silicon oil w 4.2.2.5 with ith lubricants lubricants or a mixture mixture of glycerine and tal talcum cum for coating of of the planoparallel areas of the specimen.
4.3
Specimen preparation
4.3.1
At least five test specimens specimens shall be prepar prepared ed for testing.
4.3.2 Each test specimen shall have the shape of a cylinder. The end of the test specimen shall be even and plan parallel, which is achieved by sawing both ends of the specimen. A diamond saw equipped with parallel blades is recommended. The ends shall be parallel and perpendicular to the cylinder axis (i.e. a rightangle not more than about 2° to 3°. For a rough control of evenness brush the hand over the surface. If it feels even without blemishes it shall be considered adequate, otherwise it shall be polished. After sawing/polishing the specimen shall be dried at a temperature not exceeding 25 °C. NOTE A te test st specimen should be considered to b be e dry after at at le least ast 8 h drying time a and nd w when hen two w weightings eightings performed minimum 4 h apart differ by less than 0,1 %.
4.3.3 The following dimensions, measured on the dry test specimen according to EN 12697-6, procedure D (EN 12967-29, using a vernier calliper) shall apply:
the specimen shall have a height of (60 ± 2) mm and a diameter of (148 ± 5) mm;
the height shall not vary by more than 1,0 mm and the diameter shall not vary by more than 2 mm.
4.3.4
The test shall be performed on
test specimens prepared in the laboratory by gyratory compaction (EN 12697-31);
test specimens drilled from laboratory-prepared slab of asphalt (EN 12697-33);
test specimens prepared from drilled core specimen taken from the road (EN 12697-27);
test specimens prepared in the laboratory by impact compactor (EN 12697-30).
NOTE 1
The way of compaction has a considerable impact on the results.
NOTE 2
For type testing: the compaction method is given in prEN 13108-20.
4.3.5
The bulk density of the test specimen shall be measured in accordance with EN 12697-6.
4.3.6 In case of cored specimens from the road and if the height of the individual specimen is not high enough, two specimens may be put one on top of the other (but not more than two). The same demands for evenness and plan-parallelism as for one specimen shall be met for each of the specimens as for the two put together. Each of the specimens shall have a height of at least 25 mm (the two specimens put together shall still have a height of (60 ± 2) mm). The specimens are put together without the use of any kind of substance. 4.3.7 Damage to the test specimen shall be avoided in all stages of sampling, transport and preparation before testing. During transport and storage the slab and drilled core specimen shall be fully supported to prevent deformation or damage.
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EN 12697-25:2005 (E)
4.4
Conditioning
4.4.1 The specimens shall be stored at a temperature between 5 °C and 25 °C. Test specimens shall be fully supported and not be stacked on top t op of each other. Any damage shall be prevented. 4.4.2
Testing shall start not before 2 days after compaction in the laboratory or on the road.
4.4.3
Specimens shall be cleaned if necessary by brushing or washing, as required.
4.4.4
The specimens shall be dried at ambient temperature to constant mass.
NOTE Constant mass is ob obtained tained after at least 8 h dry drying ing time and w when hen the change o off mass between two determinations at an interval of at least 4 h is less than 0,1 %.
4.4.5 To minimize the friction between the loading platens and the test specimen, the end faces of the specimen shall be smooth and plain. Brush the hand over the specimens’ surface. If it feels even without blemishes, blemishe s, it shall be considered adequate, otherwise it shall be polished or ground. NOTE 1 An adequate way to coat the en end d faces of the spe specimen cimen and minimise the friction with the platens is to apply a mixture of glycerine and talcum (or silicone oil with lubricants) to the faces, in order to obtain a smooth surface. Any surplus might be removed using an absorbent tissue. NOTE 2
Stabilize the specimen to the test temperature to within ±1,0 °C for at least 4 h and not more than 7 h.
4.4.6 NOTE
4.5
Does not apply for the surface between two specimens (see 4.3.6).
It is an advantage to be able to do this in the thermostatic chamber.
Test procedure
4.5.1
For a standard creep investigation at least five specimens shall be tested.
4.5.2
The test temperature shall be kept constant to within ±1,0 °C during the duration of the test.
NOTE 1
A typical test temperature is 40 °C.
NOTE 2
For testing according to prEN prEN 13108-20, the temperature is given given in that standard.
4.5.3 The test specimen shall be positioned well centred coaxially with the test axis between the two platens. Two displacement transducers shall be positioned on the loading platen, one opposite to the other. Then a preload shall be applied for 10 min (600 s). The accuracy on the preload control shall be ±10 % or better. 4.5.4
The deformation shall be registered after the preloading.
NOTE 1 A typical value of the preload is (72 ± 7) × 10 –3 kN (this corresponds to a pre-stress of (10 ± 1) kPa on a specimen with a diameter diameter of the loading surface of 96 mm). NOTE 2
The upper platen gives gives a constant static load (ab (about out 2 kPa), which however is not included in the cyclic load.
4.5.5 Immediatel Immediately y after the preloading time has ended, the periodic load shall be applied with a loading time for each pulse (1 ± 0,05) s. The accuracy on the period load shall be ±10 % or better. The loading pulse can be seen in Figure 3 and Figure 4. Every rest period between the pulses shall be (1 ± 0,05) s as well, meaning a frequency of approximately 0,5 Hz. Totally 3 600 pulses shall be applied (total time for the test about 2 h). NOTE 1 A typical typical value for the axia axiall load load is (724 ± 14) × 10 –3 kN (corresponding to a stress of (100 ± 2) kPa for a specimen with a diameter of 96 mm). NOTE 2
For testing according to prEN prEN 13108 13108-20, -20, the axial load load is given in that standar standard. d.
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EN 12697-25:2005 (E)
) c ( , y p o C d e l l o r t n o c n U , 9 2 : 3 1 0 1 0 2 / 8 0 / 1 3 , y b r e D f o y t i s r e v i n U , x x . r M : y p o C d e s n e c i L
4.5.6 During the test regular measurements of the total permanent deformation shall be made. As a minimum, readings shall be taken after the following loading applications: 2, 4, 6, 8, 10, 20, 40, 60, 80, 100, 200, 300 etc to 3 600. NOTE It is recommended to measure the deformation at a fixed moment in the loading/unloading cycle. Measurements are preferably taken during the rest period and as short as possible to the next loading pulse.
4.5.7 If the permanent deformation exceeds 4%microstrain a graph of total deformation versus number of loading applications shall be drawn, as it shall be seen as likely that the test specimen has been demolished (the inflexion point has been passed). The test report shall mention that the permanent deformation at 3 600 cycles exceeds 4%. The number of loading applicatio applications ns corresponding to 4% shall be reported.
4.6
Calculation and expression of results
4.6.1
Permanent deformation
The cumulative axial strain ε n after n load applications shall be calculated in percent (%) from the following equation (for a standard creep investigation, n = 3 600):
ε n
h0 − hn h0
= 100
(1)
where is the the cumulative cumulative axial strain of the specimen after n load applications, in percent (%);
ε n
average rage heigh heightt as measured measured by both displacement displacement transducers after preload of the specimen, specimen, h0 is the ave in millimetres (mm); height ight as measured by both displacement transducers after after n load applications, in hn is the average he millimetres (mm). Calculate ε n in percent (%) at 3 600 pulses from the equation above (n = 3 600). 4.6.2
Creep rate and creep modulus
If requested calculate creep rate, f c, in microstrain/loading cycle, and creep modulus, E n, in megapascal, from the following equations for a specified interval of load applications (n1, n2): f c
=
ε n 1
−
ε n 2
n1
−
n2
(2)
where f c ε n1;
is the creep rate, in microstrain/loa microstrain/loading ding pulse; n2
is the cumulative axial strain of the specimen after n1, n2 load applications (see (1)) in microstrain;
n1; n2 E n
=
is the number of repetitive load applications. σ
⋅
1 000
(3)
ε n
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I S B ) c ( , y p o C
EN 12697-25:2005 (E)
where E n is the creep modulus after n load applications, in megapascal (MPa); σ
is the applied stress, in kilopascal (kPa);
ε
is the c cumulative umulative axial strain of the specimen after n load applications (%).
d e l l o r t n o c n U , 9 2 : 3 1 0 1 0 2 / 8 0 / 1 3 , y b r e D f o y t i s r e v i n U , x x . r M : y p C o d e s n e c i L
is the c cumulative umulative axial strain of the specimen after n load applications (%).
ε n
If the permanent deformation exceeds 40 000 microstrain and the drawn graph shows that the inflexion point has been passed then the extrapolated inclination line with the least slope gives the creep rate.
4.7
Test report
The test report shall make reference to this European Standard and shall include information on the specimens and on the test results: 4.7.1
Information on the specimens
For each specimen the following information shall be provided in the test report: a)
type and origin of material tested;
b)
specimen identification number;
c)
specimen preparation m method: ethod: laborator laboratory y made (re (refer fer to relevant relevant EN standa standard) rd) or cored from the road; road;
d)
bulk de density, nsity, in megagrams per cub cubic ic metre to the nearest 0,001 0,001 Mg/m3;
e)
particulars (including the number of di discarded scarded samples).
4.7.2
Information on test conditions
For each specimen the following information shall be provided in the test report: a)
test temperature;
b)
applied stress, in kilopascal.
4.7.3
Test results
For each sample, the following information shall be provided in the test report: a)
the cum cumulative ulative a axial xial strain after 3 600 load load appli applications cations in percent (%);
b)
creep characteristics, if requested;
c)
the mean permanent deformation at 3 600 load load appl applications ications in percent (%);
d)
the mean creep characteristics, if requested.
4.8
Precision
Precision data have not yet been established. Two round robin tests were performed in 1995 and 1998 on cored samples from pavements (wearing course, binder and base courses, made of asphalt concrete and SMA). The tests were performed at 40 °C. The following precisio precision n data are estimated from these experiences:
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EN 12697-25:2005 (E)
I S B ) c ( , y p o C d e l l o r t n o c
repeatability r ; approximately 20 %,
reproducibility R; approximately 20 %.
5 5.1
Test method B — Triaxial cyclic compression test Principle
This test method determines the resistance to permanent deformation of a cylindrical specimen of bituminous mixture. The specimen is either prepared in the laboratory or cored from f rom the road. A cylindrical test specimen, maintained maintained at elevated conditioning temperature, is placed between two plan
n U , 9 2 : 3 1 0 1 0 2 / 8 0 / 1 3 , y b r e D
parallel loading platens. The specimen is subjected to a confining pressure, pressure σ a(t ) is superposed. NOTE 1
, on which a cyclic axial
σ c
The confining pressure can be static or dynamic.
The cyclic axial pressure can be: a)
a haversinusoi haversinusoidal dal pressure pressure, σ A(t ), ), is + σ a(t ) =
σ c
(t ), ), with amplitude
σ a
, as represented in Figure 6. The resulting total axial
σ V
+ σ V · (1 + sin(2π · f ·· t )). )).
(4)
σ c
Rest periods can be applied. where
σ c
f o y t i s r e v i n U , x x . r M : y p o C d e s n e c i L
is the confining stress (all around the specimen), kilopascal (kPa);
(t ) is the cycl cyclic ic axial pressure as a function of of time, in kilopascal (kPa);
σ a
in case of haversinusoidal haversinusoidal pressure, σ a(t ) is defined by σ a(t ) = σ V · (1 + sin(2π · f ·· t ))); );
σ V
b)
is the amplitude of the haversinusoidal haversinusoidal pressure, in kilopascal (kPa);
f
is the frequency, in hertz (Hz);
t
is the time.
a block-pulse pressure σ a(t ), ), with height σ B, as represented in Figure 7. The resulting total pressure, σ A(t )),, is σ c + σ a(t ))..
where is the confining pressure
σ
c
(t ) = σ B during block pulse period T 1 = 0 during rest period T 0
σ a
is the height of block pulse
σ B
In both cases a small dead load of maximum 0,02 loading) is allowed.
(for haversine loading) and 0,02
σ V
(for block-pulse
σ B
17
I
EN 12697-25:2005 (E)
S B ) c ( , y p o C d e l l o r t n o c n U , 9 2 : 3 1
Key
0 1 0 2 / 8 0 / 1 3 , y b r e D f o
Total axial pressure
σ A
Time
t
Figure 6 — Representation of the pressures exerted on the specimen in case of haversinusoidal cyclic loading
t y i s r e v i n U , x x . r M : y p o C d e s n e c i L
Key Key Total axial pressure
σ A
t
Time
T 1
Pulse duration
T 0
Rest period
1
Load
2
Pulse duration
Figure 7 — Representation of the pressures exerted on the specimen in case of block-pulse cyclic loading During the test the change in height of the specimen is measured at specified numbers of load applications. From this, the cumulative axial strain, ε n, (permanent deformation) of the test specimen is determined as a
18
I S B ) c ( , y p o C d e l l o r t n o c n U , 9 2 : 3 1 0 1 0 2 / 8 0 / 1 3
EN 12697-25:2005 (E)
function of the number of load applications. The results are represented in a creep curve as given in Figure 1. From this, the creep characteristics of the specimen are computed. NOTE 2 The actual stress conditions in the road cannot be simulated in the laboratory with simple test equipment. They depend on time (position of the wheel), the road structure, the depth in the structure, the stiffness of other layers, ... Therefore, the applied load conditions are only an approximation of the loads that occur in reality. One might suggest that application of a cyclic confining stress is to be preferred over a static confining stress. However, given the considerations just mentioned above and the fact that cyclic confining stresses require advanced and expensive equipment, it is not applied for type testing. NOTE 3 The outcome of the test is dependent on the stress conditions, on the testing temperature, temperature, the frequency and rest period and on the dimensions of the test specimens. Results obtained with a haversinusoidal loading cannot be quantitatively compared to those obtained with block-pulse loading, because of the presence of rest periods and the different shape of the signal. Results of triaxial compression tests can only be fully compared, if they are obtained under the same testing conditions. Also, in the case that the outcome of the test is used to check on the acceptability of a given mixture, the results should be evaluated with respect to specific requirements related to well-defined testing conditions.
5.2
Apparatus
5.2.1 5.2.1.1
Test system General
The axial loading system shall consist of two steel loading platens between which the specimen is placed. The static confining pressure and the axial cyclic pressure shall be applied by means of a servo-hydraulic, pneumatic, electro-magnetic or other suitable system, able to generate the required pressures with an accuracy of at least ± 2,0 %.
, y b r e D f o y t i s r e v i n U , x x . r M : y p o C d e s
The specimen shall be put in a suitable protection to separate the specimen from the confining medium. A direct contact between confining gases (air) or liquids (water, oil) on one hand and the specimen on the other hand shall be prevented. NOTE 1
Rubber foil can be used as suitable protection.
Depending on the way of applying the confining stress, three types of triaxial test systems are introduced. They are represented in Figure 8 to Figure 10. a)
In the test system represented in F Figure igure 8, the whole specimen, including including the upper and lower lower platens, shall be put in a rubber socket (or foil). The rubber socket shall seal the circumference of the platens to ensure that ingress of water, oil or air does not occur.
NOTE 2
This may be achieved by using O-rings.
The whole set-up shall be mounted in the test rig, and a pressure cell is placed around the specimen. Then the confining pressure is applied by pressurising the cell (by water, oil or air as medium). The axial cyclic load shall be subsequently applied. b)
In the test system represented in F Figure igure 9, a lateral confining confining pressure pressure shall be applied to the specimen by placing it in a “pressure ring”.
NOTE 3 This may be achieved by mounting an inner tube of an appropriate appropriate sized tyre around the specimen and inflating this tyre.
Before applying the desired lateral confining pressure, the specimen is mounted in the set-up and the loading platens are brought into contact with the t he specimen. After applying the lateral confining pressure, a constant axial stress (equal to the inflation pressure) shall be applied via the platens, to create a confining stress all around the specimen. The axial cyclic load shall be subsequently applied.
n e c i L
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EN 12697-25:2005 (E)
c)
In the test system represented in Figure 10, the confinin confining g pressure shall shall be realised realised by applying applying a partial vacuum to the specimen. The specimen shall be sealed within a rubber membrane.
NOTE 4 Sealing can be secured at either end by two O-rings which rest in purpose cut grooves around the perimeter of two specially designed platens. For the extraction of air, the lower platen may, e.g. be hollow and may, e.g. have a series of drainage holes arranged in a radial pattern on its top surface. It also may, e.g. have an outlet pipe fitted in the base which connects via a pressure regulator and gauge to a vacuum v acuum pump.
An effective confining stress shall be realised on the specimen by extracting air from the specimen. The axial cyclic load shall be subsequently applied.
Key Key 1
Actuator for dynamic pressure
4
Confining pressure
2
Pressure cell
5
Compressor
3
Specimen
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