EN 12697-26:2004

SLOVENSKI STANDARD
01-januar-2005
%LWXPHQVNH]PHVL±3UHVNXVQHPHWRGH]DYURþHDVIDOWQH]PHVL±GHO7RJRVW
Bituminous mixtures - Test methods for hot mix asphalt - Part 26: Stiffness
Asphalt - Prüfverfahren für Heißasphalt - Teil 26: Steifigkeit
Mélanges bitumineux - Méthodes d'essai pour mélange hydrocarboné a chaud - Partie
26: Module de rigidité
Ta slovenski standard je istoveten z: EN 12697-26:2004
ICS:
93.080.20 Materiali za gradnjo cest Road construction materials
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 12697-26
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2004
ICS 93.080.20
English version
Bituminous mixtures - Test methods for hot mix asphalt - Part
26: Stiffness
Mélanges bitumineux - Méthodes d'essai pour mélange Asphalt - Prüfverfahren für Heißasphalt - Teil 26: Steifigkeit
hydrocarboné à chaud - Partie 26: Rigidité
This European Standard was approved by CEN on 1 April 2004.
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 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 Central Secretariat has the same status as 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  B-1050 Brussels
© 2004 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 12697-26:2004: E
worldwide for CEN national Members.

Contents
page
1 Scope .7
2 Normative references .7
3 Terms, definitions and symbols.7
3.1 Terms and definitions .7
3.2 Symbols .8
4 Principle.9
5 Sinusoidal loading.9
5.1 Test methods.9
5.1.1 General.9
5.1.2 Bending tests .10
5.1.3 lndirect tensile test .10
5.1.4 Direct uniaxial tests.10
5.2 Loading conditions.10
5.3 Load amplitudes .10
5.4 Loading frequencies.11
6 Controlled strain rate loading.11
6.1 Test method.11
6.2 Loading conditions.11
6.3 Strain amplitudes.11
6.3.1 Preliminary test.11
6.3.2 Strain amplitudes during the test.12
6.4 Test loading times .12
7 Temperatures .12
8 Expression of results .12
9 Test report .14
9.1 General.14
9.2 Information on specimen .15
9.3 Information on test method .15
9.4 Information on the test and results.15
9.5 Optional information .15
10 Precision.15
Annex A (normative)  Two point bending test on trapezoidal specimens (2PB-TR) or on prismatic
specimens (2PB-PR).17
A.1 Principle.17
A.2 Equipment .17
A.3 Specimen preparation .18
A.4 Mode of operation.19
A.4.1 Stabilising the specimen.19
A.4.2 Procedure .19
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 Principle.21
B.2 Equipment .22
B.3 Specimen preparation .23
B.3.1 Dimensions .23
B.3.2 Sample manufacture .23
B.4 Mode of operation .24
B.4.1 Stabilising the specimen .24
B.4.2 Procedure.24
Annex C (normative)  Test applying Indirect tension to cylindrical specimens (IT-CY).26
C.1 Principle.26
C.2 Equipment .26
C.2.1 General devices .26
C.2.2 Test equipment .26
C.3 Specimen preparation.31
C.3.1 Preparation.31
C.3.2 Storage conditions.31
C.4 Mode of operation .32
C.4.1 Conditioning and test temperature.32
C.4.2 Mounting the specimen .32
C.4.3 Stiffness measurement.33
Annex D (normative)  Direct tension-compression test on cylindrical specimens (DTC-CY) .35
D.1 Principle.35
D.2 Equipment .35
D.3 Specimen preparation.35
D.4 Mode of operation .37
D.4.1 Stabilising the specimen .37
D.4.2 Procedure.37
Annex E (normative)  Test applying direct tension to cylindrical specimens (DT-CY) or to
prismatic specimens (DT-PR) .38
E.1 Principle.38
E.2 Equipment .38
E.3 Specimen preparation.38
E.3.1 Cylindrical specimen.38
E.3.2 Prismatic specimen.39
E.4 Mode of operation .39
E.4.1 Stabilisation of the specimen.39
E.4.2 Procedure.40
E.5 Derivation of the master-curve .41
E.5.1 Isotherms.41
E.5.2 Master curve at a fixed temperature.42
E.6 Determination of the stiffness modulus for the fixed loading time .44

Foreword
This document (EN 12697-26:2004) 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 January 2005, and conflicting national standards shall be withdrawn at
the latest by August 2005.
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
EN 12697-8, Bituminous mixtures — Test methods for hot mix asphalt — Part 8: Determination of void
characteristics of bituminous specimens
EN 12697-9, Bituminous mixtures — Test methods for hot mix asphalt — Part 9: Determination of the
reference density
EN 12697-10, Bituminous mixtures — Test methods for hot mix asphalt — Part 10: Compactibility
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 specimen
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
prEN 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 preparationby
impact compactor
EN 12697-31, Bituminous mixtures — Test methods for hot mix asphalt — Part 31: Specimen preparationby
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
prEN 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 pre-coated chippings for HRA
EN 12697-38, Bituminous mixtures — Test methods for hot mix asphalt — Part 38: Test equipment and
calibration
prEN 12697-39, Bituminous mixtures — Test methods for hot mix asphalt — Part 39: Binder content by
ignition
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 for hot mix asphalt — Part 42: Amount of foreign
matters in reclaimed asphalt
prEN 12697-43, Bituminous mixtures — Test methods for hot mix asphalt — Part 43: Resistance to fuel
According to the CEN/CENELEC 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.
1 Scope
This document 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
shall be respected.
The applicability of this document is described in the product standards for bituminous mixtures.
2 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
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.
3.1.1
complex modulus
relationship between stress and strain for a linear visco-elastic material submitted to a sinusoidal load wave
σ × sin (ω × t) results in a strain ε × sin (ω × (t – Φ)) that has a phase
form at time, t, where applying a stress
angle, Φ, with respect to the stress
NOTE 1 The amplitude of strain and the phase angle are functions of the frequency, ω, and the test temperature, Θ.
NOTE 2 The stress strain ratio defines the complex modulus E* as:
E* = E* ×(cos (Φ) + i ×sin (Φ)) (1)
The complex modulus is characterised by a pair of two components. This pair can be expressed in two ways: the real
component E and the imaginary components E :
1 2
E = E* ×cos (Φ ) (2)
E = E* ×sin (Φ) (3)
the absolute value of the complex modulus |E*| and the phase angle, Φ:
2 2
E* = E + E (4)
1 2
 
E
 
Φ = arctan (5)
 
E
 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 (Φ ≤ –20 °C). Then the complex modulus
reaches its highest possible value noted E .
∞
3.1.2
stiffness modulus
absolute value of the complex modulus |E*| or the value of the secant modulus
3.1.3
secant modulus
relationship between stress and strain at the loading time, t, for a material subjected to controlled strain rate
loading:
σ (t)
E(t) = (6)
ε (t)
with stress, σ(t), and strain, ε(t), at time t
NOTE 1 The strain law is:
n
ε (t) = α ×t (7)
i
where α and n are constants.
i
NOTE 2 Several successive tests may be carried out on the same specimen for different values α. For linear visco-
i
elastic materials, the secant modulus obtained for different values of α at the same temperature depends on the loading
i
time, t, only.
3.2 Symbols
For the purposes of thisdocument, the following symbols apply:
E* the complex modulus;
E the real component of the complex modulus;
E the imaginary component of the complex modulus;
E the highest possible value of the complex modulus;
∞
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;
l the length of the measurement area l , in millimetres (mm);
0 0
L the span length between outer supports in bending tests, in millimetres (mm);
t the loading time, in seconds (s);
S the stiffness modulus, in megapascals (MPa);
m
Θ the test temperature, in degrees celsius (°C);
z the displacement, in millimetres (mm);
ω the test frequency, in hertz (Hz);
Φ the phase angle, in degrees (°);
γ the form factor (a function of specimen size and form);
µ the mass factor (a function of the mass of the specimen and the mass of the movable parts that
influence the resultant force by their inertial effects);
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 Sinusoidal loading
5.1 Test methods
5.1.1 General
The following test methods can be adopted by use of the relative form and mass factor (see clause 8). The
testing procedures that shall be followed are described in annex A, B, C, D and E. 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.
5.1.2 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.
5.1.3 lndirect tensile test
The indirect tensile test option is:
 IT-CY: test applying indirect tension to cylindrical specimens, see annex C.
5.1.4 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.
5.2 Loading conditions
The amplitude and the frequency of the loading signal shall be controlled by a feedback control, which may be
based either on the force or on the displacement.
NOTE The waveform should be harmonic. Any distortion is the sign of an abnormal set up or of a resonance
phenomenon that can disturb the measurement.
5.3 Load amplitudes
The amplitude of the load shall be such that no damage can be generated during the time needed to perform
the measurements.
NOTE 1 Experience with a number of test methods has shown that for most bituminous mixtures strains should be kept
–6
at a level lower than 50 microstrain (= 50 × 10 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.
5.4 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.
6 Controlled strain rate loading
6.1 Test method
Uniaxial direct tensile test on cylindrical specimens (DT-CY 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, expresses in seconds, are compared to the complex modulus at a frequency:
f = (8)
2 π ×t
expressed in Hertz (Hz).
6.2 Loading conditions
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:
ε(t) = α ×t (9)
i
6.3 Strain amplitudes
6.3.1 Preliminary test
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.
6.3.2 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
Stiffness, 10 °C, 3 s Stiffness, 10 °C, 300 s
≥7,5 <1 ≥1
Test temperature Θ
<7,5 GPa
GPa GPa GPa
°C
Strain amplitude
microstrain
100 50 – –
≤10
10 ≤ T < 20 – – 200 100
20 ≤ T ≤ 40 – – 300 200
6.4 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.
7 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).
8 Expression of results
8.1 The measurements that shall be obtained during the test are the applied force, F, the displacement, z,
and their phase angle Φ. The places where they are measured depend on the test device (see Table 2).
8.2 The two components of the complex modulus, when required, shall be calculated in Pascals (Pa) in
using equation (10) for the real component E and equation (11) for the imaginary component E .
1 2
 F µ 
 
E = γ × × cos (Φ ) + ×ω (10)
 
z
 10 
F
 
E = γ × ×sin (Φ) (11)
z
 
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;
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.
8.3 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). For the
indirect tensile test (see annex C), the stiffness modulus is produced directly by the test equipment.
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
Form factor, γ
Type of loading
–1 Mass factor, µ
L
12L  h h 3 h 
2 2 2
a
( 2 − ) − − ln
2PB-TR 0,135 M + m
 
2h h 2 h
b(h − h )
1 1 1
 
1 2
4L
M
2PB-PR + m
bh
3 3
24L L M+m
3PB-PR
≈
4 3 3
π bh 4bh
Form factor, γ
Type of loading
Mass factor, µ
–1
L
2 2
 
L A 3 A  M m 
b b
 
 
− R()X +
4PB-PR
 
3 2 4
 
()
4 R A
bh L  
 
IT-CY × (ν + 0,27)
–
b
4h
M
DTC-CY + m
πD
DT-CY
1 0
DT-PR
a
For usual dimensions of specimens.
  L − l
b 12 L 1
, , X = co-ordinate at which the deflection is measured.
A =
R()X = ×
 
2 2 2 2
A
(3X/L − 3X /L − A /L )
 
 
9 Test report
The test report shall include the following information:
9.1 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.
9.2 Information on specimen
a) type and origin of bituminous mixture;
b) method of manufacture of the bituminous mixture;
c) method of compaction.
9.3 Information on test method
a) test method by reference to the relevant annex of this document;
b) testing equipment.
9.4 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);
e) strain or displacement;
f) stiffness modulus.
9.5 Optional information
a) complex modulus and phase angle or E and E (real and imaginary components of the complex
1 2
modulus);
b) plots of data and graphs.
10 Precision
Reproducibility and repeatability of the two-point test method on isosceles specimens (see annex A) have
been determined in accordance with ISO 5725-2 for 10 laboratories using different equipment. The
1)
experiment was done on asphalt concrete AC10 at 15 °C and 10 Hz in 2000.
Results relating to E*: (9 laboratories, 1 excluded by statistical tests):
 Average value 15°C 10 Hz: E* = 15 233 MPa;
 repeatability, standard deviation: σ = 118 MPa;
r
 repeatability, limit 95 %: r = 335 MPa;
 reproducibility, standard deviation: σ = 969 MPa;
R
1) 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.
 reproducibility, limit 95 %: R = 2 740 MPa.
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 = F × sin(ω × t), or a sinusoidal deflection, z = z × sin(ω × t), is applied to
0 0
the head of a specimens glued at its base to a stand fixed to a rigid chassis. Force, F , or deflection, z , should
0 0
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be such that it causes a strain ε ≤ 50 ×10 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, F , z and phase
0 0
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).

Key
1 Deflection at head 3 Embedment to be verified
2 Supporting plate of the metal base of the 4 Test machine
embedment
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 between 0,1 N and 100 N with an accuracy of
0,5 N up to 10 N and ±5 % above.
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 Prismatic
Trapezoidal specimens
the specimens specimens
D ≤ 14 mm D ≤ 14 mm D ≤ 22 mm D > 22 mm
Mm
B 40 56 70 75
B 40 25 25 30
E 40 25 25 35
H 120 250 250 250
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 The specimens shall be stored on a flat surface protected from the sun at a temperature below 30 °C
in conditions that prevent bending. A batch shall comprise at least four specimens. Their dimensions shall be
measured to an accuracy of 0,1 mm, and their mass to an accuracy of 0,1 g.
A.3.4 Determine the bulk density by dimensions according EN 12697-6.
A.3.5 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.
A.3.6 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.
Key
1 Groove of approximately 2 mm

2 Metal base
Figure A.2 — Geometry of the specimens Figure A.3 — Fixation of the specimen

A.4 Mode of operation
A.4.1 Stabilising the specimen
Sawed specimens shall be stored between 2 weeks and 2 months before test. For each test temperature, the
specimen shall be kept at the temperature for at least 4 h in the testing chamber. The test shall start at the
lowest temperature.
A.4.2 Procedure
A.4.2.1 The specimen shall be subjected to a sinusoidal force applied at the head for a minimum time of
30 s and a maximum time of 2 min to an imposed deflection corresponding with a strain, ε, less than
50 microstrain.
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