Bsi bs en 12697 26 2012

This document 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

BSI Standards Publication

Bituminous mixtures — Test methods for hot mix asphalt

Part 26: Stiffness

This British Standard is the UK implementation of EN 12697-26:2012.

It supersedes BS EN 12697-26:2004 which is withdrawn

The UK participation in its preparation was entrusted to TechnicalCommittee B/510/1, Asphalt products

A list of organizations represented on this committee can beobtained on request to its secretary

This publication does not purport to include all the necessaryprovisions of a contract Users are responsible for its correctapplication

© The British Standards Institution 2012 Published by BSI StandardsLimited 2012

ISBN 978 0 580 74079 4ICS 93.080.20

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 March 2012

Amendments issued since publication

Mélanges bitumineux - Méthodes d'essai pour enrobés à

chaud - Partie 26: Rigidité

Asphalt - Prüfverfahren für Heißasphalt - Teil 26: Steifigkeit

This European Standard was approved by CEN on 18 September 2011

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 CEN-CENELEC Management Centre or to any CEN member

This European Standard exists in three official versions (English, French, German) A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom

EUROPEAN COMMITTEE FOR STANDARDIZATION

C O M I T É E U R O P É E N D E N O R M A L I S A T I O N

E U R O P Ä I S C H E S K O M I T E E FÜ R N O R M U N G

Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2012 CEN All rights of exploitation in any form and by any means reserved

worldwide for CEN national Members

Ref No EN 12697-26:2012: E

Contents

Page

Foreword 4

1



2



3



3.1



3.2



4



5



5.1



5.2



5.3



5.4



5.5



6



7



7.1



7.2



7.3



8



9



10



10.1



10.2



10.3



10.4



10.5



11



Annex A (normative) Two point bending test on trapezoidal specimens (2PB-TR) or on prismatic specimens (2PB-PR) 18

A.1



A.2



A.3



A.4



Annex B (normative) Three point bending test on prismatic specimens (3PB-PR) and four point bending test on prismatic specimens (4PB-PR) 21

B.1



B.2



B.3



B.4



Annex C (normative) Test applying indirect tension to cylindrical specimens (IT-CY) 25

C.1



C.2



C.3



C.4



Annex D (normative) Direct tension-compression test on cylindrical specimens (DTC-CY) 33

D.1



D.2



D.3



D.4



Annex E (normative) Test applying direct tension to cylindrical specimens (DT-CY) or to prismatic specimens (DT-PR) 36

E.1



E.2



E.3



E.4



E.5



E.6



Annex F (normative) Test applying Cyclic indirect tension to cylindrical specimens (CIT-CY) 42

F.1



F.2



F.3



F.4



Annex G (informative) Derivation of the master curve 47

G.1



G.2



G.3



G.4



This document will supersede EN 12697-26:2004

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights

The main changes deal with putting similar procedures in all the test in the general part of the standard Also the correct wording is applied within all the test procedures

This document 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 methods 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 for hot mix asphalt — Part 5: Determination 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 bituminous specimens

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

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

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 a 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

EN 12697-40, Bituminous mixtures — Test methods for hot mix asphalt — Part 40: In situ drainability

EN 12697-41, Bituminous mixtures — Test methods for hot mix asphalt — Part 41: Resistance to de-icing fluids

EN 12697-42, Bituminous mixtures — Test methods for hot mix asphalt — Part 42: Amount of foreign matters

in reclaimed asphalt

EN 12697-43, Bituminous mixtures — Test methods for hot mix asphalt — Part 43: Resistance to fuel

EN 12697-44, Bituminous mixtures — Test methods for hot mix asphalt — Part 44; Crack propagation by semi-circular bending test

prEN 12697-45, Bituminous mixtures — Test methods for hot mix asphalt — Part 45: Saturation ageing tensile stiffness (SATS) conditioning test

prEN 12697-46, Bituminous mixtures — Test methods for hot mix asphalt — Part 46: Low temperature cracking and properties by uniaxial tension tests

EN 12697-47, Bituminous mixtures — Test methods for hot mix asphalt — Part 47: Determination of the ash content of natural asphalts

prEN 12697-48, Bituminous mixtures — Test methods for hot mix asphalt — Part 48: Inter-layer bond strength1)

prEN 12697-49, Bituminous mixtures — Test methods for hot mix asphalt — Part 49: Skid resistance of asphalt in the laboratory1)

prEN 12697-50, Bituminous mixtures — Test methods for hot mix asphalt — Part 50: Scuffing resistance of surface course1)

According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom

1) In preparation

1 Scope

This European Standard specifies the methods for characterising the stiffness of bituminous mixtures by alternative tests, including bending tests and direct and indirect tensile tests The tests are performed on compacted bituminous material under a sinusoidal loading or other controlled loading, using different types of specimens and supports

The procedure is used to rank bituminous mixtures on the basis of stiffness, as a guide to relative performance in the pavement, to obtain data for estimating the structural behaviour in the road and to judge test data according to specifications for bituminous mixtures

As this standard does not impose a particular type of testing device the precise choice of the test conditions depends on the possibilities and the working range of the used device

For the choice of specific test conditions, the requirements of the product standards for bituminous mixtures should be respected

The applicability of this document is described in the product standards for bituminous mixtures

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

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

EN 12967-31, Bituminous mixtures — Test methods for hot mix asphalt — Part 31: Specimen preparation by gyratory compactor

EN 12967-33, Bituminous mixtures — Test methods for hot mix asphalt — Part 33: Specimen prepared by roller compactor

3 Terms, definitions and symbols

3.1 Terms and definitions

For the purposes of this document, the following terms and definitions apply

3.1.2

complex modulus

relationship between stress and strain for a linear visco-elastic material submitted to a sinusoidal load wave

form at time, t, where applying a stress σ× sin (ω× t) results in a strain ε×sin (ω× (t −Φ)) that has a phase

angle, Φ, with respect to the stress

NOTE 1 The amplitude of strain and the phase angle are functions of the frequency, f, and the test temperature, Θ

NOTE 2 The stress strain ratio defines the complex modulus E* as:

)(sin)

(cos(

*

The complex modulus is characterised by a pair of two components This pair can be expressed in two ways:

the real component E1and the imaginary components E2:

)(cos

*

)(sin

2 1

NOTE 3 This second characterisation is more often used in practice In linear elastic multi-layer calculations for

instance the E* modulus is generally used as input value for Young's modulus

NOTE 4 For purely elastic materials, the phase angle is zero and then the complex modulus reduces to the Young's

modulus This happens when bituminous materials are at very low temperatures Then the complex modulus reaches its

highest possible value noted E∞

)()

(

t

t t

E

ε

σ

with stress, σ(t), and strain, ε(t), at time t

NOTE 1 The strain law is:

n i

)

(t =α ×t

where αi and n are constants

NOTE 2 Several successive tests may be carried out on the same specimen for different values αi For linear

visco-elastic materials, the secant modulus obtained for different values of αiat the same temperature depends on the loading

time, t, only

3.2 Symbols

For the purposes of this document, the following symbols apply:

E the stiffness (modulus), in megapascals (MPa);

E* the complex modulus, in megapascals (MPa);

E1 the real component of the complex modulus, in megapascals (MPa);

E2 the imaginary component of the complex modulus, in megapascals (MPa);

E∞ the highest possible value of the complex modulus, in megapascals (MPa);

F the loading force, in newtons (N);

h the mean thickness of the specimen, in millimetres (mm);

H the height of a cylindrical specimen, in millimetres (mm);

k the load area factor;

l0 the original length of the measurement area in millimetres (mm);

∆l the elongation of the measurement area in micrometers (µm);

L the span length between outer supports in bending tests, in millimetres (mm);

t the loading time, in seconds (s);

Θ the test temperature, in degrees celsius (°C);

z the displacement, in millimetres (mm);

f the test frequency in Hertz (Hz);

σ the applied stress, in megapascals (MPa);

ε the applied strain, in micrometer per meter or in microstrain (µm/m);

ω the angular speed, in radians per second (rad/s);

Φ the phase angle, in degrees (°);

γ the form factor which is a function of specimen size and form (1/mm or mm-1);

µ the mass factor which is a function of the mass of the specimen and the mass of the movable parts that influence the resultant force by their inertial effects (in g);

ν the Poisson's ratio;

∅ the diameter of a cylindrical specimen, in millimetres (mm)

4 Principle

Suitable shaped samples are deformed in their linear range, under repeated loads or controlled strain rate loads The amplitudes of the stress and strain are measured, together with the phase difference between stress and strain

5.1 Age of the specimens

Prior to the start of testing, the specimens shall be stored on a flat surface at a temperature of not more than

25 °C for between 14 days and 42 days from the time of their manufacture In the case of samples requiring cutting and/or gluing, the cutting shall be performed no more than 8 days after compaction of the asphalt and the gluing shall be performed at least 2 weeks from cutting The time of manufacture for these samples is the time when they are cut

5.2 Drying of the specimen

After sawing and before gluing and/or testing, the specimens shall be dried to constant mass in air at a relative air humidity of less than 80 % at a temperature not more than 20 °C A test specimen shall be considered to be dry after at least 8 h drying time and when two weighings performed minimum 4 h apart differ

by less than 0,1 %

5.3 Dimensions and bulk density of the specimens

The dimensions of the specimens shall be measured according to EN 12697-29

The bulk density shall be determined in accordance with EN 12697-6 or EN 12697-7 The bulk density of each specimen shall not differ by more than 1 % from the average apparent density of the batch Otherwise, the specimen shall be rejected

5.4 Temperature of the specimen before testing

The test shall not be started until the specimen has reached the required test temperature

NOTE The specimen temperature can monitored using a dummy specimen or the required temperature conditioning time can be evaluated in pre-tests The needed conditioning time depends on the test equipment, specimen size and tested material

5.5 Number of test specimens

For all the mentioned tests, the minimum amount of specimens that need to be tested to get one test result (=one stiffness modulus) is 4 specimens

6 Checking of the testing equipment

The complete testing equipment shall be checked periodically with at least one reference specimen with a known stiffness modulus (modulus and phase lag) To check the test equipment for Annexes A, B, C, or D, the

bending moment (E.I) of the specimen(s) shall be chosen to be equal to the bending moment of a normal

asphalt test specimen (adopting a stiffness modulus for the asphalt in the range of 3 GPa to 14 GPa); for Annex E and Annex F an appropriate checking specimen with a known stiffness between 3 GPa and 14 GPa shall be used The reference specimen shall be tested at not less than 6 frequencies and 2 deflection levels The back-calculated stiffness moduli shall be within 2 % with respect to the known modulus and within 1,0° for

the known phase lag If, due to the electronic components or mechanical equipment, systematic deviations (or larger deviations) of:

 the stiffness modulus is observed, all electronic components and mechanical equipment shall be checked for proper working and no procedure for the back-calculation software is permitted;

 the phase angle is observed, a correction procedure for the back-calculation software is permitted

NOTE The geometry of the reference specimen should be selected so that it will lead to a mass comparable with the mass of an asphalt specimen The clamping of the reference specimen should be equal to the procedure for an asphalt

specimen A reference material with a phase lag unequal to zero is preferred but a material like aluminium (E around

70 GPa, phase lag is zero) is also acceptable

7.1 General

The following test methods can be adopted by use of the relative form and mass factor (see Clause 9) The testing procedures that shall be followed are described in Annexes A, B, C, D, E and F If other test procedures are used to characterise stiffness properties of bituminous mixtures, the equivalence shall first by verified by comparison with one of these procedures and a statement on that equivalence shall be attached to test reports

NOTE Inter-laboratory tests have shown that the following mentioned bending tests are in good agreement provided that the equipment is carefully calibrated and that some basic guidelines are strictly followed

7.2 Tests with sinusoidal or pulse loading

7.2.1 Bending tests

The bending test options are:

 2PB-TR: test applying two point bending to trapezoidal specimens, see Annex A;

 2PB-PR: test applying two point bending to prismatic specimens, see Annex A;

 3PB-PR: test applying three point bending to prismatic specimens, see Annex B;

 4PB-PR: test applying four point bending to prismatic specimens, see Annex B

7.2.2 lndirect tensile test

The indirect tensile test options are:

 IT-CY: test applying indirect tension to cylindrical specimens, see Annex C;

 CIT-CY: test applying cyclic indirect tension to cylindrical specimens, see Annex F

7.2.3 Direct uniaxial tests

The direct uniaxial test options are:

 DTC-CY: test applying direct tension-compression to cylindrical specimens, see Annex D;

 DT-CY: test applying direct tension to cylindrical specimens, see Annex E;

 DT-PR: test applying direct tension to prismatic specimens, see Annex E

NOTE 1 Experience with a number of test methods has shown that for most bituminous mixtures strains should be kept

at a level lower than 50 microstrain (= 50×10–6 m/m) to prevent fatigue damage

NOTE 2 It is known that, beyond certain levels of strain, non-linear behaviour (e.g stress dependency) can be displayed by the material In such a case, the proportionality between stress and strain is no longer valid and the concept

of complex modulus defined above is no longer correct This limit depends on the material but it also varies with temperature for a given material

NOTE 3 Special attention should be given in the highest range of temperature Therefore, it is recommended to perform linearity tests at the highest temperature to be undertaken within the testing programme This test consists of measuring the complex modulus at a fixed frequency for an increasing range of strains (or stresses) and to determine the value of strain at which the modulus is no longer constant (starts to decrease)

NOTE 4 Attention should be paid to the danger of fatigue damage during testing by minimising the number of cycles or loading time at each applied stress level and/or minimising the number of stress levels It is recommended to carry out also a reverse scheme of stress levels in order to see if any fatigue damage has occurred (see also NOTE 1)

NOTE 5 The admissible level of deformation is determined for the direct tensile test by a preliminary test at 10 °C,

50 microstrain and loading times 3 s and 300 s

7.2.6 Loading frequencies

The range of frequencies is device dependent

NOTE 1 Most equipment is able to cover a range between 0,1 Hz and 50 Hz However, it is preferable to make it as wide as possible in order to allow a logarithmic presentation of the isotherms A typical set of frequencies could be 0,1 Hz, 0,2 Hz, 0,5 Hz, 1 Hz, 2 Hz, 5 Hz, 10 Hz, 20 Hz, 50 Hz and again the starting frequency of 0,1 Hz This last measurement

is to check that the specimen has not been damaged during the loading with various frequencies If the difference between stiffness of the specimen at the first and last measurements at identical frequency and at the same temperature is greater than 3 %, it can be concluded that the specimen is damaged and, therefore, cannot be used for further testing (e.g at different temperatures)

NOTE 2 Care should be taken to avoid resonance phenomena especially at high frequencies

NOTE 3 Care should be taken that the heat is not accumulated in the specimen in an extent that the temperature differs more than ±0,3 °C from the temperature of the climatic chamber This problem is especially dominant at prolonged measurements and/or higher frequencies

7.3 Controlled strain rate loading

7.3.1 Test method

Uniaxial direct tensile test on cylindrical or prismatic specimens (DT-CY and DT-PR see Annex E) can be adopted

NOTE The procedure gives comparable test results to sinusoidal loading for loading time less than 1 s, if the moduli

at the loading time, t, expressed in seconds, are compared to the complex modulus at a frequency:

A controlled rate displacement shall be applied to a specimen in direct tension to provide a constant strain rate

with n = 1 so that the strain law is:

For direct tensile tests, at least one element test shall be performed in accordance with Annex E in order to

determine the level of the stiffness of the mixture The conditions shall be a temperature of 10 °C, strain

amplitude of 50 microstrain, loading force F > 200 N and loading times 3 s and 300 s

7.3.3.2 Strain amplitudes during the test

The maximum strain during the test shall be less than the values given in Table 1

Table 1 — Strain expressed in microstrain to be applied during a controlled strain rate test in

accordance with the stiffness determined by a preliminary test to 50 microstrain

7.3.3.3 Test loading times

A series of tests shall be performed on the same specimen with various loading times and with the same

maximum strain given in Table 1 Four loading times shall be used for at least one test temperature, and at

least two loading times for the other test temperatures

8 Temperatures

The temperature of the climatic chamber, in the vicinity of the specimen, shall be equal to the specified

temperature to ± 0,5 °C other than for the direct tension test for which the specific temperature conditions are

given in Annex E For each test temperature, the specimen shall be placed in the climatic chamber for at least

4 h before testing

NOTE 1 Requirements for test temperatures can be determined in the product standards for the bituminous mixtures

NOTE 2 The closer tolerance for the direct tensile tests is necessary because master curves need to be derived from

the results

NOTE 3 To model reality, the temperatures should cover the extremes of climatic conditions in actual full-scale

conditions They should be close enough to allow a precise determination of a master curve by shifting the isotherms

However, Product Specifications generally define one temperature and one frequency

NOTE 4 The difference between two isotherms should not exceed 10 °C A typical set of temperatures could be -30 °C,

–20 °C, –10 °C, 0 °C, +10 °C, +15 °C, +20 °C, +30 °C, +40 °C The temperature of 40 °C should be used with care

especially for possible problems of non-linearity and also for possible creep of the specimens (especially in the case of

bending tests)

9 Expression of results

9.1 The measurements that shall be obtained during the test are the applied force, F, in Newtons (N), the

displacement, z, in millimeters (mm) and their phase angle Φ, in degrees (°) The places where they are

measured depend on the test device (see Table 2)

9.2 The two components of the complex modulus, when required, shall be calculated in MegaPascals

(MPa) in using Equation (10) for the real component E1 and Equation (11) for the imaginary component E2

)sin(

2 = × × Φ

z

F

The mechanical material characteristics shall be derived from the measurements using the specific factors

given in Table 2 where

γ is the form factor as a function of specimen size and form (1/mm);

µ is the mass factor which is a function of the mass of the specimen, M, in grams (g) and the mass of

the movable parts, m, in grams (g) that influence the resultant force by their inertial effects

NOTE The accuracy of the experimentally determined complex modulus is depending on the correct choice of the

form factor and the mass term This requires a correct evaluation of the loading conditions as well as a precise calibration

of the test set up

9.3 The stiffness modulus (the absolute value of the complex modulus E *) and the phase angle Φ, an

equivalent representation of the complex modulus, shall be derived using Equations (4) and (5)

NOTE Displacement measurements are made where the load is applied with the exception of indirect tensile method

For the indirect tensile method, the displacement is measured on the diameter that is perpendicular to the diameter to

which the load is applied

Table 2 — Form and mass factors for different specimens and loading conditions

Type of loading Form factor, γ

2 1

2 3

2 1

3

ln2

32

212

h

h h

h ) h

h ( ) h b(h

+

4

3 3 4

3

L

A bh

A

L b

( )

( )

A R

m π

M X

112

2 2 2

2/L A /L X

X/L A

A= − , X = co-ordinate at which the deflection is measured.

NOTE All dimensions in millimetres (mm); all masses in grams (g)

10 Test report

The test report shall include the following information:

10.1 General

a) name and address of the testing laboratory;

b) a unique serial number for the test report;

c) name of client;

d) the number and date of this Standard;

e) signature of person accepting technical responsibility for the test report;

f) date of issue and age of the specimens at the time of testing (in days)

10.2 Information on specimen

a) type and origin of bituminous mixture;

b) method of manufacture of the bituminous mixture;

c) method of compaction

10.3 Information on test method

a) test method by reference to the relevant annex of this document;

b) testing equipment

10.4 Information on the test and results

a) sample identification;

b) bulk density of the specimen prior to testing, and the method used for its determination;

c) temperature at which the test was carried out;

d) frequency (or load time);

Results relating to E*: (9 laboratories, 1 excluded by statistical tests):

 Average value 15 °C 10 Hz: E* = 15 233 MPa;

 repeatability, standard deviation: σr = 118 MPa;

 repeatability, limit 95 %: r = 335 MPa;

 reproducibility, standard deviation: σR = 969 MPa;

 reproducibility, limit 95 %: R = 2 740 MPa

2) DELORME, J-L, J-F CORTE and J-L GOURDON Exactitude experiments in tests relative to pavements Revue

Générale des Routes No 713 2001/03

Annex A (normative)

Two point bending test on trapezoidal specimens (2PB-TR) or on

prismatic specimens (2PB-PR)

A.1 Principle

This annex describes a method for measuring the stiffness modulus of bituminous mixtures using cantilever

bending test A sinusoidal force, F = F0× sin(ω× t), or a sinusoidal deflection, z = z0× sin(ω× t), is applied to the head of a specimens glued at its base to a stand fixed to a rigid chassis Force, F0, or deflection, z0, should be such that it causes a strain ε≤ 50 × 10–6 in the most heavily stressed part of the specimen, which is

supposed to correspond with the linear range of the bituminous mixture On the basis of, F0, z0 and phase angle, Φ, the complex modulus is calculated at different temperatures and frequencies

A.2 Equipment

A.2.1 Test machine enabling the application of sinusoidal dynamic deflection at the top of the specimen at

least within the range of frequencies from 3 Hz to 30 Hz The embedment of specimen stands in the rigid chassis shall be such that, for a given deflection, for a metal specimen, the strain, ε, measured on the test machine shall not be more than 5 % lower than the strain, ε, measured on a L-shaped frame made up of steel with a minimum thickness of 80 mm, under a force of about 50 N (see Figure A.1)

5 L-shaped steel frame

Figure A.1 — Verification of the embedment

NOTE 1 The metal specimen should have approximately the same impedance as the specimen, e.g

F/z = (350 ± 50) N/mm

NOTE 2 For example a metal parellelopipedal specimen of dimensions (13,5 ± 1) mm × (30 ± 1) mm × (250 ± 10) mm with a base, and having a Young's modulus of approximately 70 GPa, is suitable for testing this embedment

A.2.2 Ventilated thermostatic chamber in which the average temperature of the air draught near the

specimens can be fixed to ±0,3 °C at the specified test temperature throughout the whole duration of the test

If the test machine is not placed in the thermostatic chamber, the temperature of the stand of the specimen shall meet the requirements imposed to the air draught

A.2.3 Measuring equipment existing of:

A.2.3.1 Sensors, capable of measuring the dynamic force with an accuracy of ± 3 %

A.2.3.2 Sensors, capable of measuring the deflection up to 0,2 mm with an accuracy of 1 µm

A.2.3.3 Phase angle measuring device, with an accuracy of ± 1°

NOTE The phase angle due to the electronic measuring device should be deducted from the measured phase angle,

to obtain the actual phase angle, Φ The phase angle due to the electronic measuring device is measured for each test

frequency on a metal specimen as described in A.2.1

A.3 Specimen preparation

A.3.1 The specimens shall be of trapezoidal (see Figure A.2) or prismatic shape with constant thickness and shall have the dimensions given in Table A.1

Table A.1 — Minimum dimensions of the specimens Dimensions of

NOTE D is the upper sieve size of the aggregate in the mixture, in millimetres (mm)

A.3.2 Obtain the specimens by sawing from slabs made in the laboratory according EN 12697-33 or from slabs extracted from road surfaces having a thickness ≥ 60 mm The longitudinal axis of the plate shall be parallel with the horizontal compaction axis of the mixture

A.3.3 Each specimen shall be glued by its base to a metal stand (see Figure A.3) in such a manner that this operation guarantees good geometrical positioning of the specimen in relation to its stand The cap fixing the specimen to the alternating stress machine shall be glued to the head of the specimen The stand shall have a minimum thickness of 10 mm

A.4.2 The force, F0, the deflection, z0, and the phase angle, Φ, shall be measured over the last 10 s of the test

A.4.3 The complex modulus may be determined for the required temperature and for the required frequency If the master-curve has to be determined, the complex modulus shall be determined at not less than 4 temperatures separated by not more than 10 °C, and for each temperature at not less than 3 frequencies evenly spaced on a logarithmic scale with a minimum ratio of 10 between the extreme frequencies

Annex B (normative)

Three point bending test on prismatic specimens (3PB-PR) and four

point bending test on prismatic specimens (4PB-PR)

B.1 Principle

This annex describes a method for measuring the stiffness of bituminous mixtures using bending test A prismatic specimen is subjected to three-point or to four-point periodic bending with free rotation and (horizontal) translation at all load and reaction points The bending is realised by the movement of the centre load point(s) in vertical direction perpendicular to the longitudinal axis of the specimen The vertical positions

of the two end points remain fixed The applied periodic displacement is symmetrical about the zero, and sinusoidal, and the displacement amplitude shall be constant as a function of time During the test, the force needed for the deformation of the specimen is measured as a function of time as well as the phase lag between the force signal and the displacement signal From this, the stiffness modulus of the tested material

6 return to original position

7 free translation and rotation

Figure B.1 — Basic principals of 4-point bending

B.2 Equipment

B.2.1 Loading system, consisting of a bending bed The load shall be applied to the specimen by means of

loading jack(s) via the bending bed There shall be:

 one jack on the middle clamp at x = L/2 for the three point bending test;

 two jacks on the inner clamps at x = A and x=L – A for the four point bending test

B.2.2 Clamping device, capable of clamping a specimen (beam) in the bending frame in order to provide

horizontal translation and rotation freedom at all supports The back-calculated stiffness modulus for a

reference beam with a known stiffness modulus shall be within 2 % for the modulus and within 0,5° for the

phase lag (see B.2.8)

In the case of the four point bending test, the assumed pure bending between the two inner clamps shall be

checked by measuring the deflections at the inner clamp (x =A) and in the middle of the specimen (x=L/2)

The ratio of the amplitudes of the centre deflection and the deflection at the inner clamps shall be a constant

that is defined as:

(

)

A

A L L

R

A R A

Z

L

Z

434

43)2/(

)()

NOTE A should be chosen in the interval 0,25 < A/L < 0,4 but preferably close to one third of the effective length L

(ASTM configuration) In that case, the ratio will be 1,15 If A/L is chosen outside this interval, the equations given in this

annex are no longer applicable without introducing substantial errors

B.2.3 Control system, for the movement of the actuator, in order to control the bending of the specimen, in

such a manner as to be conform to the requirements laid down for the applied displacement (see B.4.2)

NOTE It is recommended that the control system should include a programmable function generator and a control

circuit with which the desired load signal can be generated The control system should ensure that the controlled

displacement of the specimen does not show oscillations during the test

B.2.4 Load cell, with a measuring range of at least ± 2 000 N and with an accuracy of 1 % The force shall

be measured midway between the centre two clamps

NOTE The resonance frequency of the load cell and the coupled moving mass should be at least a factor of 10

higher than the test frequency

B.2.5 Displacement transducer, with a measuring range of about ± 1,0 mm and with an accuracy of 1 %

The displacement shall be measured at the diagonal centre of the top surface or that on the lower surface of

the specimen

NOTE The resonance frequency of the transducer and the coupled moving mass should be at least a factor of 10

higher than the test frequency

B.2.6 Electronic data registration equipment, low-noise amplifiers with a range that approximately

corresponds to the maximum values of the measuring range of the transducers Measuring instruments with

analogue or digital displays shall be such that the measuring amplifiers can be read with a resolution of 1 N for

the force and 1 µm for the displacement

NOTE The dynamic behaviour of the transducers and the electronic measuring apparatus can be the cause of

measuring errors that are considerably greater than the maximum permissible values It is recommended that the

supplier’s specifications are checked in this respect Another important factor to be considered is whether the electronic

equipment is adequately shielded against the influence of external electrical and magnetic sources of interference capable

of producing measuring errors

B.2.7 Thermostatic chamber, in which a constant test temperature can be maintained to within an

accuracy of ± 0,5 °C in the vicinity of the specimens

NOTE It is recommended that a sufficiently large thermostatic chamber is chosen, so that additional specimens can

B.3 Specimen preparation

B.3.1 Dimensions

B.3.1.1 The specimen shall have the shape of a prismatic beam with the following nominal proportions and tolerances:

 the total length Ltot shall not exceed the effective length by more than 10 %;

 the difference between maximum and minimum measured value per dimension shall be 1,0 mm at the most;

 the angle between adjacent longitudinal surfaces shall not deviate from a right angle by more than 1°

NOTE It is also recommended that:

— the effective length L should not be less than six times whatever the highest value is for the width B or the height H

— the width B and the height H should be at least three times the maximum grain size D in the tested material

B.3.1.2 The total length shall be measured four times with a ruler with an accuracy of 1,0 mm in the centre of the top and the bottom surfaces The height and the width shall be measured with vernier callipers

with an accuracy of 0,1 mm at the places where the clamps are to be installed (x = 0, x = L/2 and x = L [3PB] or

x = 0, x = A, x = L − A and x = L [4PB]) The length of the test specimen shall be calculated as the arithmetic

mean of the length measurements The width and the height of the specimen shall be calculated similarly from the width measurements and the height measurements, respectively Specimens not complying with the specimen requirements shall not be tested

NOTE Technical limitations of the apparatus in combination with the maximum grain size in the asphalt mixture can

make it difficult to comply with the requirements as to width B, B/D > 3 and H/D > 3 If any of these requirements are not met, the test will not be strictly in accordance with this annex and this non-compliance should be explicitly mentioned in the report

B.3.2 Sample manufacture

The specimens subject to the test shall be obtained by sawing from slabs made in laboratory or taken from

road layers The slabs made in the laboratory shall have at least a thickness of the required height H plus

20 mm The beams shall be sawn from the middle The distance of the beam to the border of the slab shall be

at least 20 mm In principle, the same procedure holds for beams sawn from slabs taken from road layers If

the thickness of the road layer is too small to meet the requirement with respect to the ratio between height H and the maximum grain size D, the beams shall be rotated over an angle of 90° In such cases, the width B of

the beam shall not be able to meet the requirement and shall be reported

The longitudinal axis of the specimen shall be parallel with the major direction of compaction

B.4 Procedure

B.4.1 Three (3PB) or four (4PB) clamps shall be fastened to the specimen at mutual spacings (centre to

centre) of L/2 and L/2 for the 3PB test and A, L − 2A and A for the 4PB test The tolerance on the spacings

NOTE Hence, a horizontal longitudinal specimen surface by its orientation in the slab should become a vertical specimen surface by its orientation in the test set-up

B.4.3 The beam shall be weighed as well as all the moving parts between the load cell and the beam (e.g moving frame, clamps and deflection sensor) and the points on the beam where these masses have there influence shall be determined in order to correctly calculate the mass factor

NOTE Normally, the locations where the masses act are at the inner clamp(s)

B.4.4 The specimen shall be subjected to a sinusoidal force in order to obtain the required strain amplitude of (50 ± 3) microstrain The deflection amplitude shall stay within 2 % of the nominal value

B.4.5 The force, F0, the deflection, z0, and the phase angle, Φ, shall be recorded, together with the test temperature and the frequency

B.4.6 The initial stiffness modulus shall be determined as the modulus for a load cycle between the 45thand the 100th load repetition

NOTE The initial stiffness modulus is typically determined at the 100th cycle because this is often defined as the initial stiffness modulus value and, more importantly, the required parameters (e.g strain amplitude) should be constant by the cycle at which the stiffness modulus is determined

Annex C (normative) Test applying indirect tension to cylindrical specimens (IT-CY)

C.1 Principle

This annex describes a method for measuring the elastic stiffness of bituminous mixtures using an indirect tensile test The method is applicable to cylindrical specimens of various diameters and thickness, manufactured in the laboratory or cored from a road layer

C.2 Equipment

C.2.1 General devices

C.2.1.1 Thermometer and/or thermocouples and/or platinum resistance sensors, of appropriate range, which shall be capable of measuring to ± 0,1 °C for determining the temperature of the specimen and the storage and test environment

C.2.1.2 Jig, to hold a cylinder of test material for cutting of specimens

C.2.1.3 Saw, capable of cutting and trimming specimens to the required dimensions

NOTE A diamond-tipped saw blade is recommended

C.2.2 Test equipment

C.2.2.1 Steel load-frame

NOTE A suitable example is shown in Figure C.1

C.2.2.2 Two stainless steel loading strips, conforming to Table C.1 The face in contact with the specimen shall be concave and shall extend over the full width of the specimen The edges of the loading strips shall be rounded to avoid cutting the specimen during testing A means of centralising the lower strip with the loading axis of the steel load frame shall be provided The upper strip shall make contact with the loading system via a spherical seating