SIST EN 12697-26:2018+A1:2022
(Main)Bituminous mixtures - Test methods - Part 26: Stiffness
Bituminous mixtures - Test methods - Part 26: Stiffness
This European Standard specifies the methods for characterizing 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 operating scope and working range of the device used.
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.
Asphalt - Prüfverfahren - Teil 26: Steifigkeit
Mélanges bitumineux - Méthodes d'essai- Partie 26 : Rigidité
Bitumenske zmesi - Preskusne metode - 26. del: Togost (vključno z dopolnilom A1)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2022
Bitumenske zmesi - Preskusne metode - 26. del: Togost (vključno z dopolnilom A1)
Bituminous mixtures - Test methods - Part 26: Stiffness
Asphalt - Prüfverfahren - Teil 26: Steifigkeit
Mélanges bitumineux - Méthodes d'essai- Partie 26 : Rigidité
Ta slovenski standard je istoveten z: EN 12697-26:2018+A1:2022
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.
EN 12697-26:2018+A1
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2022
EUROPÄISCHE NORM
ICS 93.080.20 Supersedes EN 12697-26:2018
English Version
Bituminous mixtures - Test methods - Part 26: Stiffness
Mélanges bitumineux - Méthodes d'essai- Partie 26 : Asphalt - Prüfverfahren - Teil 26: Steifigkeit
Rigidité
This European Standard was approved by CEN on 26 February 2018 and includes Amendment 1 approved by CEN on 7
September 2022.
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, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 12697-26:2018+A1:2022 E
worldwide for CEN national Members.
Contents Page
European foreword . 5
1 Scope . 6
2 Normative references . 6
3 Terms, definitions and symbols . 6
3.1 Terms and definitions . 6
3.2 Symbols . 8
4 Principle . 9
5 Sample preparation . 9
5.1 Age of the specimens . 9
5.2 Drying of the specimens . 9
5.3 Dimensions and bulk density of the specimens . 9
5.4 Number of test specimens . 10
6 Checking of the testing equipment . 10
7 Test methods . 10
7.1 General . 10
7.2 Codification of tests . 10
7.2.1 Sinusoidal bending tests . 10
7.2.2 lndirect tensile test (pulse or cyclic) . 11
7.2.3 Cyclic or monotonous uniaxial tests . 11
7.2.4 Loading conditions . 11
7.2.5 Load amplitudes . 11
7.2.6 Loading frequencies . 11
7.3 Controlled strain rate loading . 12
7.3.1 Test method . 12
7.3.2 Loading conditions . 12
7.3.3 Strain amplitudes for direct tensile tests . 12
8 Temperatures . 13
9 Expression of results . 13
10 Test report . 15
10.1 Introduction . 15
10.2 General . 15
10.3 Information on specimens . 15
10.4 Information on test method . 15
10.5 Information on the test and results . 16
10.6 Optional information . 16
11 Precision . 16
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 Procedure . 19
Annex B (normative) Three point bending test on prismatic specimens (3PB-PR) and four
point bending test on prismatic specimens (4PB-PR). 20
B.1 Principle . 20
B.2 Equipment . 21
B.3 Specimen preparation . 22
B.3.1 Dimensions . 22
B.3.2 Sample manufacture . 22
B.4 Procedure . 23
Annex C (normative) Test applying indirect tension to cylindrical specimens (IT-CY) . 24
C.1 Principle . 24
C.2 Equipment . 24
C.2.1 General devices . 24
C.2.2 Test equipment . 24
C.3 Specimen preparation . 29
C.4 Mode of operation . 30
C.4.1 Mounting the specimen . 30
C.4.2 Stiffness measurement . 30
C.4.2.1 Conditioning load pulses . 30
C.4.2.2 Deformation measuring . 30
C.4.2.3 Calculation of the stiffness modulus . 30
C.4.2.4 Stiffness modulus of the specimen . 31
Annex D (normative) Direct tension-compression test on cylindrical specimens (DTC-CY) . 32
D.1 Principle . 32
D.2 Equipment . 32
D.3 Specimen preparation . 32
D.4 Mode of operation . 34
D.4.1 Stabilizing the specimen . 34
D.4.2 Procedure . 34
Annex E (normative) Test applying direct tension to cylindrical specimens (DT-CY) or to
prismatic specimens (DT-PR) . 35
E.1 Principle . 35
E.2 Equipment . 35
E.3 Specimen preparation . 35
E.3.1 Cylindrical specimen . 35
E.3.2 Prismatic specimen . 36
E.4 Mode of operation . 36
E.4.1 Stabilization of the specimen . 36
E.4.1.1 Temperature stabilization . 36
E.4.1.2 Preliminary mechanical stabilization . 36
E.4.1.3 Mechanical stabilization between tests . 37
E.4.2 Procedure. 37
E.5 Derivation of the master-curve - Isotherms . 38
Annex F (normative) Test applying cyclic indirect tension to cylindrical specimens (CIT-CY) . 39
F.1 Principle . 39
F.2 Equipment . 39
F.2.1 Test machine . 39
F.2.2 Loading. 39
F.2.3 Displacement . 39
F.2.4 Thermostatic chamber . 41
F.2.5 Recording and measuring system . 41
F.2.6 Loading strips . 41
F.3 Specimen preparation . 41
F.3.1 Test specimen . 41
F.3.2 Specimen dimensions . 42
F.4 Mode of operation . 42
F.4.1 Test temperature . 42
F.4.2 Mounting the specimen . 42
F.4.3 Procedure. 42
F.4.3.1 General . 42
F.4.3.2 Load frequency . 43
F.4.3.3 Definition of the lower load level . 43
F.4.3.4 Definition of the upper load level. 43
F.4.4 Checking of specimen deterioration . 43
Annex G (informative) Derivation of the master curve . 44
G.1 Principle . 44
G.2 Theoretical background . 45
G.3 Experimental data. 46
G.4 Test report . 47
European foreword
This document (EN 12697-26:2018+A1:2022) has been prepared by Technical Committee CEN/TC 227
“Road materials”, the secretariat of which is held by !BSI".
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 April 2023, and conflicting national standards shall be
withdrawn at the latest by April 2023.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN not be held responsible for identifying any or all such patent rights.
This document includes Amendment 1 approved by CEN on 7 September 2022.
This document supersedes EN 12697-26:2018.
!deleted text"
The start and finish of text introduced or altered by amendment is indicated in the text by tags !".
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
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, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.
1 Scope
This European Standard specifies the methods for characterizing 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 operating scope and working range of the device used.
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.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. 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 - Part 6: Determination of bulk density of bituminous
specimens
EN 12697-7, Bituminous mixtures - Test methods - Part 7: Determination of the bulk density of bituminous
specimens by gamma rays
EN 12697-27, Bituminous mixtures - Test methods - Part 27: Sampling
EN 12697-29, Bituminous mixtures - Test methods - Part 29: Determination of the dimensions of a
bituminous specimen
EN 12697-31, Bituminous mixtures - Test methods - Part 31: Specimen preparation by gyratory
compactor
EN 12697-33, Bituminous mixtures - Test method - 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
stiffness modulus
relationship between maximum applied stress and maximum measured strain response and expressed
as:
σ
E= (1)
ε
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
The amplitude of strain and the phase angle are functions of the frequency, f, and the test temperature,
Θ
The stress strain ratio defines the complex modulus E* as:
EE* *⋅(cos()Φ+ i⋅sin (Φ)) (2)
The complex modulus depends on the frequency f and the temperature θ. The complex modulus is
characterised in two ways:
1. By the real component E and the imaginary components E :
1 2
E E*⋅cos(Φ) (3)
EE= *⋅Φsin ( ) (4)
2. By the absolute value of the complex modulus ∣E*∣ and the phase angle, Φ:
2 2
(5)
E* EE+
E
(6)
Φ= arctan
E
1
This second characterization 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 1 to entry: 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 .
∞
=
=
=
3.1.3
secant modulus
relationship between stress and strain at the loading time, t, for a material subjected to controlled
loading (force or displacement):
σ ()t
(7)
E()t =
ε ()t
with stress, σ(t), and strain, ε(t), at time t
Note 1 to entry: The strain law is
n
ε ()ttα⋅
(8)
i
where α and n are constants.
i
Note 2 to entry: Several successive tests can be carried out on the same specimen for different values of α . For
i
linear visco-elastic materials, the secant modulus obtained for different values of α at the same temperature
i
depends on the loading time, t, only.
3.2 Symbols
For the purposes of this document, the following symbols apply:
D maximum aggregate size in an asphalt mix in millimetre (mm);
E the elastic stiffness (modulus), in megapascals (MPa);
E* the visco-elastic complex modulus, in megapascals (MPa);
|E*| absolute modulus of the complex modulus, in megapascals (MPa);
E the real component of the complex modulus, in megapascals (MPa);
E 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);
l the original length of the measurement area in millimetres (mm);
Δl the elongation of the measurement area in micrometers (µm);
L the span length between outer supports in bending tests, in millimetres (mm);
m mass of the movable parts in grams (g);
M weight of the sample in grams (g);
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);
ε the maximum strain applied to the test specimen, in micrometer per meter or in microstrain
max
(μm/m);
ω the angular speed, in radians per second (rad/s);
φ the phase shift between the force and the displacement in degrees (°);
Φ the modulus phase angle of the material (argument), in degrees (°);
γ −1
the form factor which is a function of specimen size and form (1/mm or mm );
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 grams (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. From the measured force and deformation signal, amplitudes of the stress and strain, and the
phase angle between both are calculated. Based on measured stress and strain desired moduli can be
calculated.
5 Sample preparation
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 20 °C for between 14 d and 42 d 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 d 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.
NOTE 1 The storage time influences the mechanical properties of the specimen.
NOTE 2 For test purposes other than for CE marking, different storage times can be applied.
5.2 Drying of the specimens
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 density of the batch. Otherwise, the
specimen shall be rejected.
5.4 Number of test specimens
For all test methods described in this standard, the stiffness modulus of a minimum of 4 specimens shall
be tested. The average of these results determine the stiffness modulus for the tested mix.
6 Checking of the testing equipment
The completely assembled 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 and B, 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 Annexes C, D, E and F an appropriate checking specimen with a known
stiffness between 3 GPa and 14 GPa shall be used.
The checking should be applied for each applied test temperature. For cyclic tests (Annex A, B, D, and F)
the reference specimen shall be tested at not less than 6 frequencies and 2 deformation levels. For
impulsive tests (Annex C), the reference specimen shall be submitted to a minimum of 4 trials in regular
test conditions. For monotonic tests (Annex E), the reference specimen shall be tested in at least 4
loading times and 2 displacement amplitudes.
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 are observed, all electronic components and/or mechanical equipment shall
be checked for proper working. No procedure for use of back-calculation software is permitted;
— the phase angle is observed, a correction procedure for the back-calculation software is permitted.
The geometry of the reference specimen shall be selected so that it will lead to a mass comparable with
the mass of an asphalt specimen. The clamping of the reference specimen shall 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) or comparable materials is also
acceptable.
7 Test methods
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 characterize stiffness properties of bituminous mixtures, the equivalence shall
first be verified by comparison with one of these procedures and a statement on that equivalence shall
be attached to the test reports.
7.2 Codification of tests
7.2.1 Sinusoidal 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 (pulse or cyclic)
The indirect tensile test options are:
— IT-CY: test applying pulse indirect tension to cylindrical specimens, see Annex C;
— CIT-CY: test applying cyclic indirect tension to cylindrical specimens, see Annex F.
7.2.3 Cyclic or monotonous uniaxial tests
The direct uniaxial test options are:
— DTC-CY: test applying cyclic tension-compression to cylindrical specimens, see Annex D;
— DT-CY: test applying monotonous direct tension to cylindrical specimens, see Annex E;
— DT-PR: test applying monotonous direct tension to prismatic specimens, see Annex E.
7.2.4 Loading conditions
The specific parameters of the loading signal (amplitude, frequency, loading and/or rest time) shall be
controlled by a feedback control, which may be based either on the force or on the displacement.
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.
7.2.5 Load amplitudes
The amplitude of the load shall be such that no damage can be generated during the time needed to
perform the measurements.
Experience with a number of test methods has shown that for most bituminous mixtures strains should
−6
be kept at a level lower than 50 microstrain (= 50 × 10 m/m) to prevent fatigue damage.
NOTE 1 It is known that, beyond certain levels of strain, nonlinear 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.
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).
Attention should be paid to the danger of fatigue damage during testing by minimizing the number of
cycles or loading time at each applied stress level and/or minimizing 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 2 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 Most equipment is able to cover a range between 0,1 Hz and 50 Hz. However, it is preferable to make
the range of loading frequencies 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).
Care should be taken to avoid resonance phenomena especially at high 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 in Hertz
(Hz):
(9)
f =
2π⋅t
7.3.2 Loading conditions
A controlled rate displacement shall be applied to a specimen in direct tension to provide a constant
strain rate so that the strain law is:
εα()tt⋅ (10)
i
7.3.3 Strain amplitudes for direct tensile tests
7.3.3.1 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.
7.3.3.2 Strain amplitudes during the test
The maximum strain during the direct tensile tests 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
≤ 10 100 50 – –
10 ≤ Θ < 20 – – 200 100
20 ≤ Θ ≤ 40 – – 300 200
=
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. Also a dummy specimen which is close to the tested specimen with an inside
thermocouple can be used for the temperature check. For each test temperature, unless check testing
indicates that a consistent temperature is reached in a shorter period of time, 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.
To model reality, the temperatures should cover the extremes of climatic conditions in actual full-scale
conditions. To allow a precise determination of a master curve of the stiffness modulus by shifting the
isotherms, the test temperatures should be chosen close enough to each other. However, Product
Specifications generally define one temperature and one frequency.
To determine a master curve of the stiffness modulus, 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 as it may result in possible
problems of nonlinearity and also for possible creep of the specimens (especially in the case of bending
tests).
9 Expression of results
The measurements that shall be obtained during the test are the applied force, F, in newton (N), the
displacement, z, in millimetres (mm) and their phase angle φ, in degrees (°). The places where they are
measured depend on the test device (see Table 2).
The two components of the complex modulus, when required, shall be calculated in megapascal (MPa)
in using Formula (10) for the real component E and Formula (11) for the imaginary component E .
1 2
F
−6 2
E= γ ⋅ ⋅ cosϕ +1 0 ⋅⋅µω
( ) (11)
z
F
E= γ ⋅⋅ sinϕ (12)
( )
z
The mechanical material characteristics shall be derived from the measurements using the specific
factors given in Table 2.
NOTE 1 The accuracy of the experimentally determined complex modulus is dependent 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.
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 Formulae (5) and (6).
NOTE 2 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 (see Figure C.1 and F.1).
Table 2 — Form and mass factors for different specimens and loading conditions (all dimensions
in millimetres (mm); all masses in grams (g))
Form factor, γ
Mass factor, μ
Type of loading
−1
(g)
mm
12L hh 3 h
22 2
()2− −− ln
2PB-TR 0,135 Mm+
b(h− h ) 22h h h
1 2 11 1
M
4L
2PB-PR + m
bh 4
M +m
24LL
3PB-PR ≈
43 3
πbh 4bh 2
LA 3 A Mm
a a
− RX +
4PB-PR ( )
4
RA
bh 4 L ( )
π
IT-CY and
⋅+(ν 0,27)
–
CIT-CY
b
Form factor, γ
Mass factor, μ
Type of loading
−1
(g)
mm
4h M
+ m
DTC-CY
π D 2
!
DT-CY
1 0
DT-PR
"
12 L 1 Ll−
a
A=
RX ⋅ , , X = coordinate at which the deflection is
( )
2 2 2 2
A (3X / L−−3X / L A / L )
measured.
10 Test report
10.1 Introduction
The test report shall include the following information:
10.2 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.
10.3 Information on specimens
a) type and/or origin of bituminous mixture;
b) method of manufacture of the bituminous mixture;
c) method of compaction;
d) date of issue and age of the specimens at the time of testing (in days).
10.4 Information on test method
a) test method by reference to the relevant annex of this document;
=
b) testing equipment.
10.5 Information on the test and results
a) sample identification;
b) bulk density of the specimens prior to testing, and the method used for their determination;
c) temperature at which the test was carried out;
d) frequency (or load time);
e) strain or displacement;
f) stiffness modulus.
10.6 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.
11 Precision
Reproducibility and repeatability of the two-point test method on isosceles specimens (see Annex A:
2PB-TR) have been determined in accordance with ISO 5725-2 for 10 laboratories using different
)
eq
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