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EUROPEAN STANDARD EN 12697-24

NORME EUROPÉENNE
EUROPÄISCHE NORM July 2004

ICS 93.080.20

English version

Bituminous mixtures - Test methods for hot mix asphalt - Part
24: Resistance to fatigue

Mélanges bitumineux - Méthodes d'essai pour enrobés à Asphalt - Prüfverfahren für Heißasphalt - Teil 24:
chaud - Partie 24: Résistance à la fatigue Beständigkeit gegen Ermüdung

This European Standard was approved by CEN on 2 March 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 12697-24:2004: E
worldwide for CEN national Members.

EN 12697-24:2004 (E)

Contents
page

Foreword..............................................................................................................................................................5
1 Scope ......................................................................................................................................................8
2 Normative references ............................................................................................................................8
3 Terms, definitions, symbols and abbreviations .................................................................................8
3.1 General....................................................................................................................................................8
3.2 Two-point bending test on trapezoidal specimens ............................................................................9
3.3 Two-point bending test on prismatic shaped specimens ...............................................................10
3.4 Three-point bending test on prismatic shaped specimens.............................................................13
3.5 Four-point bending test on prismatic shaped specimens ..............................................................14
3.6 Indirect tensile test on cylindrical shaped specimens ....................................................................19
3.6.1 Symbols ................................................................................................................................................19
4 Failure ...................................................................................................................................................20
5 Calculations..........................................................................................................................................20
6 Summary of the procedures ...............................................................................................................20
6.1 Two-point bending test on trapezoidal specimens ..........................................................................20
6.2 Two-point bending test on prismatic shaped specimens ...............................................................20
6.3 Three-point bending test on prismatic shaped specimens.............................................................20
6.4 Four-point bending test on prismatic shaped specimens ..............................................................20
6.5 Indirect tensile test on cylindrical shaped specimens ....................................................................21
7 Test report ............................................................................................................................................21
Annex A (normative) Two-point bending test on trapezoidal shaped specimens ....................................22
A.1 Principle................................................................................................................................................22
A.1.1 General..................................................................................................................................................22
A.1.2 Element test..........................................................................................................................................22
A.1.3 Fatigue line ...........................................................................................................................................23
A.2 Equipment ............................................................................................................................................23
A.2.1 Test machine ........................................................................................................................................23
A.2.2 Thermostatic chamber ........................................................................................................................23
A.2.3 Measuring equipment..........................................................................................................................24
A.3 Specimen preparation .........................................................................................................................24
A.3.1 Sawing and storing..............................................................................................................................24
A.3.2 Characteristics of the specimens ......................................................................................................25
A.3.3 Embedding Check................................................................................................................................25
A.3.4 Stabilisation of the specimens ...........................................................................................................26
A.3.5 Gluing the ends....................................................................................................................................26
A.4 Procedure .............................................................................................................................................27
A.4.1 Preparing the test equipment .............................................................................................................27
A.4.2 Carrying out the fatigue test...............................................................................................................27
A.4.3 Choice of the strain .............................................................................................................................27
A.4.4 Number of element tests .....................................................................................................................28
A.5 Calculation and expression of results...............................................................................................28
A.6 Test report ............................................................................................................................................30
A.7 Precision...............................................................................................................................................30
Annex B (normative) Two-point bending test on prismatic shaped specimens .......................................31
B.1 Principle................................................................................................................................................31

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EN 12697-24:2004 (E)

B.2 Equipment ............................................................................................................................................31
B.2.1 Test machine........................................................................................................................................31
B.2.2 Thermostatic chamber ........................................................................................................................31
B.2.3 Measuring equipment .........................................................................................................................31
B.3 Specimen preparation.........................................................................................................................32
B.3.1 Sawing and storing .............................................................................................................................32
B.3.2 Characteristics of the specimens ......................................................................................................32
B.3.3 Stabilisation of the specimens...........................................................................................................32
B.3.4 Gluing the ends ...................................................................................................................................32
B.4 Procedure .............................................................................................................................................32
B.4.1 Preparing the test equipment.............................................................................................................32
B.4.2 Carrying out the fatigue test...............................................................................................................33
B.4.3 Choice of the tension ..........................................................................................................................33
B.5 Calculation and expression of results ..............................................................................................33
B.6 Test report ............................................................................................................................................35
B.7 Precision...............................................................................................................................................36
Annex C (normative) Three-point bending test on prismatic shaped specimens ....................................37
C.1 Principle................................................................................................................................................37
C.1.1 General .................................................................................................................................................37
C.1.2 Element test .........................................................................................................................................37
C.1.3 Fatigue line...........................................................................................................................................37
C.2 Equipment ............................................................................................................................................37
C.2.1 Test machine........................................................................................................................................37
C.2.2 Load cell ...............................................................................................................................................37
C.2.3 Extensometer and displacement sensor ..........................................................................................37
C.2.4 Clamping device ..................................................................................................................................38
C.2.5 Data acquisition equipment ...............................................................................................................38
C.2.6 Thermostatic chamber ........................................................................................................................38
C.2.7 Other general equipment ....................................................................................................................38
C.2.8 Check on the operation of the complete equipment and the mounting of the specimen............38
C.3 Specimen preparation.........................................................................................................................38
C.3.1 Manufacturing and sawing .................................................................................................................38
C.3.2 Bulk density .........................................................................................................................................38
C.3.3 Storing ..................................................................................................................................................38
C.3.4 Clamping devices preparation ...........................................................................................................39
C.4 Procedure .............................................................................................................................................39
C.4.1 Preparing the test equipment.............................................................................................................39
C.4.2 Carrying out the fatigue test...............................................................................................................39
C.4.3 Load function, extensometer signal function, and displacement function recording .................39
C.4.4 End of test ............................................................................................................................................40
C.5 Calculation and expression of results ..............................................................................................40
C.5.1 Calculation of the stress function and the strain function at a cycle ............................................40
C.5.2 Calculation of the dynamic modulus, phase difference angle, and density of dissipated
energy at one cycle .............................................................................................................................41
C.5.3 Determination of the fatigue law and energy law.............................................................................42
C.6 Test report ............................................................................................................................................43
C.7 Precision...............................................................................................................................................43
Annex D (normative) Four-point bending test on prismatic shaped specimens ......................................44
D.1 Principle................................................................................................................................................44
D.1.1 General .................................................................................................................................................44
D.1.2 Element test .........................................................................................................................................44
D.1.3 Fatigue line...........................................................................................................................................45
D.2 Equipment ............................................................................................................................................46
D.2.1 Test machine........................................................................................................................................46
D.2.2 Clamping device ..................................................................................................................................46
D.2.3 Thermostatic chamber ........................................................................................................................46
D.2.4 Electronic data registration equipment.............................................................................................46
D.2.5 Check on the operation of the complete equipment and the mounting of the specimen............47

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................1 Preparing the test equipment ......................48 D.......47 D..................6 Mounting............4....................EN 12697-24:2004 (E) D.3.................................................55 E...........4 Storage..48 D..............................2.............................2 Carrying out the fatigue test.52 E.................................................................................................................................................................................................................................................................................52 E...................................................................................................................................................................................................1 Dimensions................................52 E..4 Thermostatic chamber ...........................................................................................................1 Test specimen .....................................................................49 D......7 Precision..............51 D....................55 E.........................................................6 Test report ...................................................................................................................................................................................................................................................3......3....................................................................................................................6 Test report ..................52 E...1 Principle.....................................5 Calculation and reporting of results .......................................................................................2 Sawing ....................................................................................................52 E...........4 Conditioning.......................................52 E..............................................59 E.........................................56 E........................................................................................................................3....................................48 D....................................................................................................................................................................................................................................3...3 Specimen preparation ..4 Procedure ....................................................................48 D........................................2...............................3....52 E......8 Glue ..........................................................................48 D.....................................................4...........55 E..................................4.........................................................................54 E.............................................................................................................................................................................................48 D.................................49 D..........................................................................................................................................6 Loading frame .....................................2 Loading ..............................2.........................5 Recording and measuring system ....3...................................................................47 D.......................................................................................4 Data processing ...........................................3 Choice of test conditions.............................................................................2 Equipment ............53 E...........................................................................................................................2.........................................................59 Bibliography ........3..............3................................3 Drying...................................................5 Condition .........55 E....................................3 Displacement....................55 E...............................................................................................................................3 Position of the deformation and loading strips.........1 Test machine ....................................................................................54 E.....................................................................................4...2.....51 Annex E (normative) Indirect tensile test on cylindrical shaped specimens..............2 Specimen dimensions ..7 Positioning rig.............................3....................................................................2.................................4 Procedure .............................................................................50 D....................................................................2.......................................52 E....3 Specimen preparation ..............................................................7 Precision......60 4 ..............5 Calculation and expression of results..........2.....................................................................................................................................................................................48 D.................................................................56 E................................50 D...............................................

Bituminous mixtures — Test methods for hot mix asphalt — Part 12: Determination of the water sensitivity of bituminous specimens. EN 12697-16. Bituminous mixtures — Test methods for hot mix asphalt — Part 9: Determination of the reference density. Bituminous mixtures — Test methods for hot mix asphalt — Part 15: Determination of the segregation sensitivity. EN 12697-5. EN 12697-8. EN 12697-7. EN 12697-15. EN 12697-14. This European Standard shall be given the status of a national standard. EN 12697-6. Bituminous mixtures — Test methods for hot mix asphalt — Part 6: Determination of bulk density of bituminous specimens. This document is one of a series of standards as listed below: EN 12697-1. EN 12697-4. Bituminous mixtures — Test methods for hot mix asphalt — Part 14: Water content. the secretariat of which is held by DIN. EN 12697-2. Bituminous mixtures — Test methods for hot mix asphalt — Part 2: determination of particle size distribution. EN 12697-11. Bituminous mixtures — Test methods for hot mix asphalt — Part 4: Binder recovery: Fractionating column. Bituminous mixtures — Test methods for hot mix asphalt — Part 1: Soluble binder content. EN 12697-9. EN 12697-13. Bituminous mixtures — Test methods for hot mix asphalt — Part 3: Binder recovery: Rotary evaporator. Bituminous mixtures — Test methods for hot mix asphalt — Part 10: Compactibility. and conflicting national standards shall be withdrawn at the latest by August 2005. Bituminous mixtures — Test methods for hot mix asphalt — Part 7: Determination of bulk density of bituminous specimens by gamma rays. EN 12697-24:2004 (E) Foreword This document (EN 12697-24:2004) has been prepared by Technical Committee CEN/TC 227 “Road materials”. Bituminous mixtures — Test methods for hot mix asphalt — Part 8: Determination of void characteristics of bituminous specimens. EN 12697-12. Bituminous mixtures — Test methods for hot mix asphalt — Part 11: Determination of the affinity between aggregate and bitumen. Bituminous mixtures — Test methods for hot mix asphalt — Part 5: Determination of the maximum density. EN 12697-10. 5 . EN 12697-3. at the latest by January 2005. Bituminous mixtures — Test methods for hot mix asphalt — Part 13: Temperature measurement. Bituminous mixtures — Test methods for hot mix asphalt — Part 16: Abrasion by studded tyres. either by publication of an identical text or by endorsement.

Bituminous mixtures — Test methods for hot mix asphalt — Part 28: Preparation of samples for determining binder content. Bituminous mixtures — Test methods for hot mix asphalt — Part 25: Cyclic compression test. Bituminous mixtures — Test methods for hot mix asphalt — Part 34: Marshall test. EN 12697-22. Bituminous mixtures — Test methods for hot mix asphalt — Part 37: Hot sand test for the adhesivity of binder on precoated chippings for HRA. EN 12697-32. EN 12697-30. EN 12697-31. EN 12697-24. EN 12697-19. EN 12697-33. EN 12697-36. Bituminous mixtures — Test methods for hot mix asphalt — Part 18: Binder drainage. EN 12697-34. Bituminous mixtures — Test methods for hot mix asphalt — Part 38: Common equipment and calibration. Bituminous mixtures — Test methods for hot mix asphalt — Part 30: Specimen preparation. prEN 12697-25.EN 12697-24:2004 (E) EN 12697-17. Bituminous mixtures — Test methods for hot mix asphalt — Part 22: Wheel tracking. EN 12697-18. Bituminous mixtures — Test methods for hot mix asphalt — Part 23: Determination of the indirect tensile strength of bituminous specimens. Bituminous mixtures — Test methods for hot mix asphalt — Part 31: Specimen preparation. Bituminous mixtures — Test methods for hot mix asphalt — Part 35: Laboratory mixing. EN 12697-28. 6 . 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 29: Determination of the dimensions of a bituminous specimen. EN 12697-29. EN 12697-26. Bituminous mixtures — Test methods for hot mix asphalt — Part 20: Indentation using cube or Marshall specimens. Bituminous mixtures — Test methods for hot mix asphalt — Part 26: Stiffness. Bituminous mixtures — Test methods for hot mix asphalt — Part 33: Specimen prepared by roller compactor. water content and grading. EN 12697-23. EN 12697-38. EN 12697-20. Bituminous mixtures — Test methods for hot mix asphalt — Part 24: Resistance to fatigue. Bituminous mixtures — Test methods for hot mix asphalt — Part 27: Sampling. prEN 12697-35. impact compactor. gyratory compactor. Bituminous mixtures — Test methods for hot mix asphalt — Part 32: Laboratory compaction of bituminous mixtures by a vibratory compactor. Bituminous mixtures — Test methods for hot mix asphalt — Part 17: Partial loss of porous asphalt specimen. Bituminous mixtures — Test methods for hot mix asphalt — Part 19: Permeability of specimen. Bituminous mixtures — Test methods for hot mix asphalt — Part 21: Indentation using plate specimens. EN 12697-21. EN 12697-27.

Poland. Greece. Finland. Estonia. Bituminous mixtures — Test methods for hot mix asphalt — Part 42: Amount of foreign matters in reclaimed asphalt. Spain. Netherlands. Switzerland and United Kingdom. Bituminous mixtures — Test methods for hot mix asphalt — Part 43: Resistance to fuel. EN 12697-24:2004 (E) prEN 12697-39. France. Italy. 7 . Denmark. Slovakia. According to the CEN/CENELEC Internal Regulations. Belgium. Latvia. Czech Republic. Hungary. Lithuania. prEN 12697-40. Slovenia. Norway. Luxembourg. Ireland. the national standards organizations of the following countries are bound to implement this European Standard: Austria. Portugal. prEN 12697-43. Germany. Iceland. prEN 12697-42. prEN 12697-41. Cyprus. Bituminous mixtures — Test methods for hot mix asphalt — Part 41: Resistance to de-icing fluids. Sweden. No existing European Standard is superseded. Bituminous mixtures — Test methods for hot mix asphalt — Part 39: Binder content by ignition. Malta. Bituminous mixtures — Test methods for hot mix asphalt — Part 40: In-situ drainability.

as a guide to relative performance in the pavement. The applicability of this document is described in the product standards for bituminous mixtures. 3 Terms. the precise choice of the test conditions depends on the possibilities and the working range of the used device. For dated references. symbols and abbreviations apply. symbols and abbreviations For the purposes of this document. The tests are performed on compacted bituminous material under a sinusoidal loading or other controlled loading.1 fatigue reduction of strength of a material under repeated loading when compared to the strength under a single load 3. the latest edition of the referenced document (including any amendments) applies. EN 12967-33. For the choice of specific test conditions. including bending tests and direct and indirect tensile tests. the following terms and definitions.1.1. EN 12697-26. gyratory compactor. Because this document does not impose a particular type of testing device. Bituminous mixtures — Test methods for hot mix asphalt — Part 26: Stiffness. to obtain data for estimating the structural behaviour in the road and to judge test data according to specifications for bituminous mixtures. 2 Normative references The following referenced documents are indispensable for the application of this document. 3. Bituminous mixtures — Test methods for hot mix asphalt — Part 31: Specimen preparation. only the edition cited applies. EN 12697-27. EN 12697-29. Results obtained from different test methods are not assured to be comparable. Bituminous mixtures — Test methods for hot mix asphalt — Part 33: Specimen preparation by roller compactor. Bituminous mixtures — Test methods for hot mix asphalt — Part 6: Determination of bulk density of bituminous specimen. definitions.1 General 3. The procedure is used to rank bituminous mixtures on the basis of resistance to fatigue. Bituminous mixtures — Test methods for hot mix asphalt — Part 29: Determination of the dimensions of bituminous specimen. EN 12697-6. when the complex stiffness modulus has decreased to half its initial value 8 .2 conventional criteria of failure (constant displacement) number of load applications. Bituminous mixtures — Test methods for hot mix asphalt — Part 27: Sampling. EN 12697-31. Nf/50. using different types of specimens and supports. For undated references. the requirements of the product standards for bituminous mixtures shall be respected.EN 12697-24:2004 (E) 1 Scope This document specifies the methods for characterising the fatigue of bituminous mixtures by alternative tests.

e.0.4 conventional criteria of fatigue (constant force) when the displacement of a specimen under constant strength at the head has increased to the double that at the start of the test 3.3 initial complex stiffness modulus complex stiffness modulus.1.g. b.1. frequency and loading mode.j. or constant force level. to be converted into maximum strain NOTE Kε and its relationship with the parameters mentioned above is the following: Kε × z = ε (1) B 2 × ( B − b) 2 Kε = [ ( b )] 4b × h 2 × (b − B) × (3 B − b) + 2 B 2 × ln B (2) 9 .2 Two-point bending test on trapezoidal specimens 3.2.1 constant relative to maximum strain constant that enables the head displacement z of the trapezoidal specimen of dimensions [B. Smix. and or any other constant loading condition) 3.k corresponding with the conventional failure criterion at the set of test conditions k (temperature. after 100 load applications 3. h]. constant deflection level.1. e. EN 12697-24:2004 (E) 3. to which a bending strain level ε is applied.5 fatigue life of a specimen number of cycles Ni.

in metres (m) ei is the thickness. relative to the maximum strain.3. with a strain of 1 microstrain (µstrain) being equal to 10 by convention: i is the Index of the specimen for an element test (varies from 1 to n) hi is the height.1 average fatigue life of a series of specimens average from a series of n specimens at the level of tension σj max given by equation (3) n e N j max = × ∑ n i =1 ln ( N ij ) (3) 10 . log(εi)) 1/b is the slope of the fatigue line log(ε) is the average value of log(εi) S log(ε) is the standard deviation of log(εi) S log(N) is the standard deviation of log(Νi) 6 ε6 is the strain corresponding with 10 cycles sN is the estimation of the residual standard deviation of the decimal logarithms of fatigue lives ∆ε6 is the quality index of the test n is the number of specimens 3.2 Symbols -6 The symbols are as follows. in metres (m) vi is the void content of the specimen i by geometric method.EN 12697-24:2004 (E) 3.2. in metres (m) bi is the small base. in metres (m) Bi is the large base. in metres (m) εi is the maximum relative strain of specimen i corresponding with the displacement imposed at the head Ni is the conventional fatigue life of specimen i a is the ordinate of the fatigue line according to the equation log(N) = a + (1/b) log(ε) r2 is the linear correlation cofficient (log(Ni). in inverse metres (m ) zi is the amplitude of displacement imposed at the head of specimen i. in per cent (%) –1 Kεi is the constant.3 Two-point bending test on prismatic shaped specimens 3.

6 hi Kσ i = (6) bi2 × ei 11 . j is the number of the tension level σj max.3. 3. Nij is the conventional fatigue life at the level of tension σj max. σjmax the greatest relative tension of the specimen. n is the number of specimens at the level of tension σj max. corresponding to the strength. in millimetre (mm). 3. Nj max is the average number of cycles obtained at the level of tension σj max. to be converted to a maximum tension NOTE Kε i.3. EN 12697-24:2004 (E) where Njmax is the average number of cycles obtained at the level of tension σj max. Nij is the fatigue life of the specimen i at the level of tension σj max.3 constants for consideration of the geometry of specimen constants that enable the strength of the head Pij of the specimen i of dimensions bi . J is the number at the level of tension σj max. n is the number of specimens at the level of tension σj max. is as follows: K σ i × Pij = σ j max (5) where Kσi is the constants for consideration of the geometry of specimen at constant strength. in Newton (N). and its relationship with the parameters mentioned above. to which a bending strength is applied. εjmax is the maximum relative strain of the specimen corresponding with the displacement imposed at the head. with which the head is applied.ei and hi. with which the head is applied. l is the thickness.2 standard deviation of the fatigue life of a series of specimens standard deviation of the natural logarithm of the fatigue life obtained at the level of tension σj max for n repetitions given by equation (4) n ∑ (ln ( N ij ) − ln ( N ε j max ))2 1 S j max = × (4) (n − 1) i =1 where sj max is the estimation of the standard deviation. Pij is the amplitude of the strength.

in millimetre (mm).3. in millimetres (mm) bI is (A) small base or (B) base.1 Sample i hI is the height.4 Symbols –6 The symbols are as follows.3.4. in per cent (%) Kσi is the constant for consideration of the geometry of specimen at constant strength.4. in grams (g) vi% is the vacuum achieved by the geometric method as a proportion of atmospheric pressure. 3. with a strain of 1 microstrain (µstrain) being equal to 10 by convention: 3. in millimetres (mm) mI is the mass.4. in millimetre (mm). in inverse –1 millimetres (mm ) 3.4 Fatigue life relative to sample i at the strain level εj Nij is the conventional fatigue life. in megapascals (MPa) sσ x y is the estimation of the residual standard deviation of the natural logarithms of fatigue lives ∆σˆ 6 is the confidence of σ̂ 6 for a probability of 95 % 12 . corresponding to the strength.EN 12697-24:2004 (E) where Kσi is the constant for consideration of the geometry of specimen at constant strength (factor in accordance to EN 12697-26). in Newtons (N) σj max is the greatest relative tension of the specimen. ei is the width.3.3. 3.3 Fatigue life of a specimen i at the level of tension σj max Nij is the fatigue life.4. with which the head is applied 3. 3.2 Strength at head and greatest tension at specimen i at level of tension εj max Pij is the amplitude of the strength with which the head is applied.5 Fatigue line pσ is the slope of fatigue line ln(σj max) = f (ln(Nij)) 6 σ̂ 6 is the tension corresponding with 10 cycles. bi is the base.3. in millimetre (mm).4. in millimetres (mm) eI is the thickness. hi is the height.3.

in millimetres (mm) 13 . in megajoules per cubic metre (MJ/m ) EXT is the instant extensometer signal. in microns (µm) 3 DDE is the density of dissipated energy. in radians (rad) Dc is the displacement at instant t. in millimetres (mm) MD is the dynamic modulus.3. in millimetres (mm) Bt is the phase angle of the approximate stress function. in radians (rad) Bε is the phase angle of the approximate strain function. in megajoules per cubic metre 3 (MJ/m ) b is the width of specimen. in megapascals (MPa) W is the total density of dissipated energy throughout the whole test.6 Fatigue life of a series of n specimens (A) at a strain level εjmax or (B) at the level of tension σj max Nεjmax is the average number of cycles obtained at the level of tension σj max l is the number at the level of tension σj max n is the number of specimens at the level of tension σj max 3.1 Symbols The symbols are as follows: 2At is the amplitude of the approximate stress function.4. in megapascals (MPa) 2At is the amplitude of the approximate strain function B is the measuring base of the extensometer. in millimetres (mm) e is the thickness of specimen. in megajoules per cubic metre 3 (MJ/m ) 3 DDE (x) is the density of dissipated energy at cycle x. EN 12697-24:2004 (E) N is the number of element tests (number of specimens at the level of tension σj max times the number of levels) where N = n*l sN is the estimation of the standard deviation of ln(Nij) 3.4.4 Three-point bending test on prismatic shaped specimens 3. in megapascals (MPa) N is the number of cycle at end of test P is the instant load. in microns (µm) 2D0 is the total amplitude of displacement function. in millimetres (mm) L is the distance between supports. in megapascals (MPa) or megajoules per cubic metre (MJ/m ) DE(total) is the total density of dissipated energy throughout the whole test.

This set contains the applied frequency f0.1 (complex) stiffness modulus ratio S = Smix.5.5. e. and or any other constant loading condition) 3. in Hertz (Hz) m is (N – 200)/500 t is the time.0 in megapascals (MPa) of the complex modulus and for the initial phase lag φo in degrees of the complex modulus taken at the 100th load application 3. in megapascals (MPa) Φ is the phase difference angle. constant deflection level. and or constant dissipated energy per cycle) 3.n × eiφ of the calculated stress and strain during cycle n in the specimen NOTE The stiffness modulus defines the relationship between stress and strain for a linear viscoelastic material subjected to sinusoidal loading.4 test condition k set of conditions at which a specimen is tested. k = (7) m 14 .5 Four-point bending test on prismatic shaped specimens 3. in seconds (s) ε is the instant strain or half cyclic amplitude of strain function at cycle 200 εa is the approximate strain function value εc is the cyclic amplitude of strain function ε6 6 is the strain at 10 cycles σ is the instant stress.g. in degrees (°) 3.j. corresponding with the chosen failure criteria j (e. in megapascals (MPa) σc is the cyclic amplitude of stress function.g. k ) ei = 1 N J.2 initial (complex) stiffness modulus values for the initial modulus Smix.5. frequency and loading mode. the test temperature Θ and the loading mode (constant deflection.EN 12697-24:2004 (E) f is the wave frequency.5. j.k number of cycles for specimen i.5. 3. conventional failure j = f/50) at the set of test conditions k (temperature. or constant force. or constant force level.3 fatigue life Ni. in megapascals (MPa) σa is the approximate stress function value.5 average fatigue life of a series of specimens value defined according to a failure criteria j on a series of m specimens at a test condition k given by: m ∑ ln ( N i.

15 . k ) − ln ( N j. EN 12697-24:2004 (E) 3. k = × ln ( N i.13 co-ordinate x distance between x and the left outer clamp (0 ≤ x ≤ L/2). in millimetres (mm) 3. In good working equipment. in millimetres (mm) 3.14 co-ordinate xs co-ordinate x where the deflection is measured (A ≤ xs ≤ L/2).5. in kilograms per second (kg/s) NOTE This coefficient can only be established by tuning the equipment with a reference beam of which the stiffness modulus and (material) phase angle are known.5.7 total length Ltot total length of the prismatic specimen. in millimetres (mm) 3.16 mass Mbeam total mass of the prismatic beam.15 density ρ 3 geometrical density of the specimen.10 height H height of the prismatic specimen.5. k ) (8) (m − 1) i =1 3. in millimetres (mm) 3.17 damping coefficient T coefficient needed for calculation of the system losses. in kilograms (kg) 3.5.8 effective length L distance between the two outer clamps.5. in millimetres (mm) 3.9 width B width of the prismatic specimen. j. in millimetres (mm) 3.5. the coefficient T can be neglected (adopting a zero value).12 co-ordinate A distance between the left outer (x = 0) and left inner clamp (x = A).5. in kilograms per cubic metre (kg/m ) M beam × 10 9 ρ = (9) ( H × L × B) 3.6 standard deviation of the fatigue life for a series of specimens natural logarithm of the average fatigue life for a failure criteria j at a test condition k given by: ∑( ) m 1 2 St j. in millimetres (mm) 3.11 mid-span length a distance between the two inner clamps.5. in millimetres (mm) 3.5.5.5.5.

20 equivalent coefficient for damping weighed coefficient for the damping in the system in kilograms per second (kg/s).23 frequency f0 [Hz] and circular frequency ω0 [rad/s] frequency of the applied sinusoidal load: ω 0 = 2π × f 0 (13) 3.5.24 inertia function I(xs) dimensionless function depending on the distance xs in order to account for mass inertia effects: Z ( xs ) I ( xs ) = M eq × × ω 02 × 10 −3 (14) F0 3. sensor (Msensor) and clamps (Mclamp) which value depends on the place where the deflection Z(xs) is measured: R( xs ) R ( xs ) M eq = × M beam + × M clamp + M sensor (11) π4 R( A) 3.19 equivalent mass Meq weighed mass in kilograms (kg) of the moving parts of beam (Mbeam).EN 12697-24:2004 (E) 3. measured on or between the two inner clamps at a distance xs from the left outer clamp.21 deflection Z(xs) amplitude of the deflection of the beam during one cycle.18 weighing function R(x) dimensionless function depending on the distance x to the left outer clamp.5. in millimetres (mm) 3.5.25 damping function J(xs) dimensionless function depending on the distance xs in order to account for damping (non viscous) effects in the system (system losses): Z(xs ) J(xs ) = Teq × × ω 0 × 10 -3 (15) F0 16 .5.22 force F0 amplitude of the total force at the two inner clamps in Newtons (N) 3.5. the co-ordinate A of the left inner clamp and the effective length L between the two outer clamps: 12 L3 R( x) = (10) A × (3 L × x − 3 x 2 − A 2 ) 3.5.5. the value of which depends on the place where the deflection Z(xs) is measured R(xs ) Teq = ×T (12) R(A) 3.5.

EN 12697-24:2004 (E)

3.5.26
*
measured phase lag ϕ (xs)
measured phase lag in degrees during one cycle between the applied sinusoidal load and the measured
deflection Z(xs)

3.5.27
system phase lag θ (xs)
calculated phase lag in degrees during one cycle representing the system losses:

 π  Teq × ω 0
tanθ ×  = (16)
 180  M eq × ω 02

3.5.28
phase lag φ
calculated phase lag in degrees during one cycle between the occurring stress and strain in the specimen at
the applied frequency:

 π 
sin  φ * (x ) × − J (x )
 π   s 180  s
tan φ ×  = (17)
 180   π 
cos φ * (x ) × + I(x )
 s 180  s

3.5.29
modulus Smix of the complex (stiffness) modulus or dynamic stiffness modulus
calculated modulus of the complex modulus for the specimen during one cycle, in megapascals (MPa):

12F0 × L3
Smix = × 1+ 2[ cos(φ*(xs )) × I(xs ) − sin(φ*(xs ))× J(xs )] + [I 2(xs ) + J 2(xs )] (18)
Z(xs ) × R(xs ) × B × H3

3.5.30
constant K relative to (maximum) strain
constant that enables the calculation of the maximum bending strain amplitude at the place where the
–1
deflection is measured, in inverse millimetres (mm ):

H×A
K ( xs ) = × R( xs ) (19)
4 L3

3.5.31
strain amplitude ε = ε (xs)
maximum strain amplitude during one cycle which occurs between the two inner clamps, in micron per metre
(µm/m):

ε = K ( x s ) × Z ( xs ) × 10 6 (20)

3.5.32
stress amplitude σ
maximum stress amplitude during one cycle which occurs between the two inner clamps, in megapascals
(MPa):

σ = S mix × ε (21)

17

EN 12697-24:2004 (E)

3.5.33
dissipated energy per cycle
dissipated viscous energy in the beam per unit volume ∆Wdis and per cycle, in kilojoules per cubic metre
3
(kJ/m ) that, for sinusoidal strain and stress signals, is:


( )
∆Wdis = π × ε × σ × sin  φ xs ×
π 
180
 (22)
 

3.5.34
cumulated dissipated energy
summation of the dissipated energies per cycle up to cycle n:

n
Wdis,n(m) = ∑ ∆Wdis,i (23)
i =1

NOTE If the measurements are taken at intervals n(i), it is recommended to use the trapezium rule:

m
[ (
Wdis, n(m) = n(1) × ∆Wdis, n(1) + ∑ 0,5 × (n(i + 1) − n(i ) )× ∆Wdis, n(i + 1) + ∆Wdis, n(i) )] (24)
i =1

3.5.35
amplitude
half the difference between the maximum and the minimum of a (sinusoidal) signal measured during one cycle

3.5.36
measuring error
difference between the true value of a physical quantity and the value indicated by the measuring instrument,
expressed as a proportion of the true value, in per cent (%)

3.5.37
accuracy class
permissible measuring error in the output signal of a transducer or sensor

3.5.38 Symbols

The symbols are as follows:

A1 is the estimate of the slope, p

A0 is the estimation of the level of loading, Q

B is the width of the prismatic specimen, in millimetres (mm)

D is the maximum nominal grain size of the mixture being tested, in millimetres (mm)

H is the height of the prismatic specimen, in millimetres (mm)

L is the effective length of the prismatic specimen, in millimetres (mm)

Ltot is the total length of the prismatic specimen, in millimetres (mm)

Mbeam is the mass of the whole beam whole beam without the masses of the mounted clamps, in grams (g)

Mclamps is the masses of the two inner clamps, including the mass of the adhesive, and the mass of the load
frame between the load cell and the jack, in grams (g)

18

EN 12697-24:2004 (E)

Msensor is the mass of the moving parts of the sensor, in grams (g)

Meq is the equivalent mass, in grams (g)

Ni,j,k is the length of life for specimen number i the chosen failure criteria j and the set of test conditions k
is cycles

Nf/50 is the number of load applications at conventional failure when the modulus of the (complex)
stiffness modulus has decreased to half its initial value
6
Q is the level of the loading mode test condition corresponding to 10 cycles for the fatigue life
according to the chosen failure criteria, k

∆Q is the confidence interval relative to Q

Smix is the initial value of the calculated modulus

Sx/y is the estimation of the standard deviation of the residual dispersion of the natural logarithms of
fatigue lives, σx/y

T is the coefficient for the system losses in the interpretation equations for Young’s modulus

f0 is the frequency of the sinusoidal load applications

p is the slope of the fatigue line

r is the correlation coefficient of the regression

x is the distance from end of sample, in millimetres (mm)

xs is the distance from the end of the specimen to where the sensor is placed, in millimetres (mm)

εi th
is the initial strain amplitude measured at the 100 load cycle

ω0 is the test frequency

Θ is the test temperature, in degrees Celsius (°C)

3.6 Indirect tensile test on cylindrical shaped specimens

3.6.1 Symbols

The symbols are as follows

∆Η is the horizontal deformation, in millimetres (mm)

Nf is the number of load applications at fatigue life

P is the maximum load, in Newtons (N)

k, n are material constants

t is the specimen thickness, in millimetres (mm)

σo is the tensile stress at specimen centre, in megapascals (MPa)

εo is the tensile strain in µε at the centre of the specimen

19

The method can be used for bituminous mixture specimens with maximum aggregate size of 22 mm or for samples from road layers with a thickness of at least 50 mm. in the vertical direction. the method shall be carried out on several elements tested at a controlled temperature. and hence a constant strain. 6. The method can be used for bituminous mixtures with maximum aggregate size of up to 20 mm. The behaviour is characterised through the determination of the fatigue law in terms of strain (relation between strain and number of load cycles at failure) and the associated energy law. The vertical position of the end-bearings (outer clamps) shall be fixed. the criterion used shall be included the test report. with controlled displacement by three point bending using prismatic beam shaped specimens. 5 Calculations The test loads and frequencies shall be selected so that the results are calculated by interpolation and not be extrapolation. This load configuration shall create a constant moment. For a given frequency of sinusoidal displacement.1. on specimens prepared in a laboratory or obtained from road layers with a thickness of at least 40 mm.4 Four-point bending test on prismatic shaped specimens This method characterises the behaviour of bituminous mixtures under fatigue loading in a four-point bending test equipment of which the inner and outer clamps are symmetrically placed and using slender rectangular shaped specimens (prismatic beams). the method shall be carried out on several elements tested in a ventilated atmosphere at a controlled temperature. perpendicular to the longitudinal axis of the beam.2 Two-point bending test on prismatic shaped specimens This method characterises the behaviour of bituminous mixtures under fatigue loading by 2-point-bending using square-prismatic shaped specimens. The prismatic beam shall be subjected to four-point periodic bending with free rotation and translation at all load and reaction points. The method can be used for bituminous mixtures with a maximum aggregate size of up to 20 mm on specimens prepared in a laboratory or obtained from road layers with a thickness of at least 40 mm. between the two inner clamps. the test can be performed using the same principle but with adapted specimen sizes. 6. In such cases.1 Two-point bending test on trapezoidal specimens This method characterises the behaviour of bituminous mixtures under fatigue loading with controlled displacement by two point bending using trapezoidal shaped specimens. The bending shall be realised by loading the two inner load points (inner clamps). in millimetres (mm) µε –6 is the microstrain = 10 strain 4 Failure The conventional failure criterion for the type of test undertaken. The applied load shall be 20 . as defined in 3. 6 Summary of the procedures 6. 6. For a given frequency of sinusoidal displacement.EN 12697-24:2004 (E) Ω is the specimen diameter. shall be used to determine the failure life of a material unless otherwise prescribed. For mixtures with an upper size D between 20 mm and 40 mm.3 Three-point bending test on prismatic shaped specimens This method characterises the behaviour of bituminous mixes under fatigue loading.

k) details not provided for in this document. A cylinder-shaped test specimen shall be exposed to repeated compressive loads with a haversine load signal through the vertical diametrical plane. EN 12697-24:2004 (E) sinusoidal.5 Indirect tensile test on cylindrical shaped specimens This method characterises the behaviour of bituminous mixtures under repeated load fatigue testing with a constant load mode using an indirect tensile load. A cylindrical specimen manufactured in a laboratory or cored from a road layer can be used in this test. c) average air void content in the specimen (EN 12697-8). 21 . 6. i) title of the relevant annex of this document. b) date that the test was undertaken. This loading develops a relatively uniform tensile stress perpendicular to the direction of the applied load and along the vertical diametrical plane.). frequency. The fracture life shall be determined as the total number of load applications before fracture of the specimen occurs. d) method of manufacture or sampling. the deflection and the phase lag between these two signals shall be measured as a function of time. h) representation of the fatigue line. During the test the load. etc. if applicable. The fatigue characteristics of the material tested shall be determined with these measurements. g) average number of cycles and the standard deviation obtained for each strain or stress level. e) conditions of the fatigue testing (temperature. l) any incidents which may have an effect on the results. which causes the specimen to fail by splitting along the central part of the vertical diameter. The resulting horizontal deformation of the specimen shall be measured and an assumed Poisson's ratio used to calculate the tensile strain at the centre of the specimen. j) other results required by the relevant annex. needed for the bending of the specimen. f) chosen failure criterion (if not the conventional failure criterion). 7 Test report The test report shall include: a) identification of the mixture.

1.1.3 For a given frequency of sinusoidal displacement. as shown in Figure A.1. A.EN 12697-24:2004 (E) Annex A (normative) Two-point bending test on trapezoidal shaped specimens A.  measuring the fatigue life of the test piece when the failure criterion is achieved.1 This annex describes a method to characterise the behaviour of bituminous mixtures under fati- gue loading with controlled displacement by two point bending using trapezoidal shaped specimens.1 Principle A. but with adapted specimen sizes. 22 . the test can be performed using the same principle.1. on specimens prepared in a laboratory or obtained from road layers with a thickness of at least 40 mm. A.  recording. the change in the force at head amplitude relative to the reaction of the test piece.1. A.2 The method can be used for bituminous mixtures with aggregate having an upper sieve size of 20 mm.2 Element test An element test shall consist of:  imposing a constant amplitude sinusoidal displacement at the head of an isosceles trapezoidal console test piece. For mixtures with an upper sieve size D between 20 mm and 40 mm.1.1.1.1. the method shall be carried out on several elements tested in a ventilated atmosphere with a controlled temperature.1 General A. during this.

1 Test machine The test machine shall consist of a system enabling to apply a sinusoidal displacement to the head of the specimen with a fixed frequency. Using these results. The fatigue line shall be estimated in a bi-logarithmic system as a linear regression 6 of fatigue life versus amplitude levels.3 Fatigue line The fatigue line of the mixture element tests at the different displacement amplitude levels that the tests are carried out shall be drawn. Constant amplitude sinusoidal displacement 3. if required for special purposes. A. The standard deviation of the residual dispersion of fatigue life sN and the quality index relative to ε6. Results derived from tests at different frequencies may not be directly comparable.1 µm/Ν during the test.2 Thermostatic chamber The thermostatic chamber shall be ventilated and capable of allowing the temperature of the metal base of the specimens and the average temperature of the air draught at tens of millimetres from the specimens to be fixed with an accuracy of ±1 °C throughout the duration of the test. Groove in the metal base Figure A.1. at other frequencies ±4 %. The displacement shall vary less than 0.2. Force at head amplitude relative to the reaction of the test piece 2.2 Equipment A. The test machine shall be capable of applying the load to specimens at a frequency of (25 ± 1) Hz and. it should be included in the test report. the strain corresponding to an average of 10 cycles ε6 and the slope of the fatigue line 1/b shall be determined. EN 12697-24:2004 (E) Key 1.2. A. ∆ ε6 may also be calculated. NOTE If a frequency other than 25 Hz is used. 23 .1 — Sinusoidal displacement at the head of specimen A.

5 × 10 m.2.1 The specimens shall be of an isosceles trapezoidal shape. A. the indication of displacement in dynamic procedure shall be equal to the static one to less than 2 %. A.2.2. If calibration is undertaken by a static method.3.3. from slabs made in laboratory according to EN 12967-33.1 Force Equipment for measuring the force at the head of the specimens shall measure to an accuracy of ±2 % for values ≥200 N and to an accuracy of ±2 N for values <200 N. and of constant thickness as shown in Figure A.1 Sawing and storing A.1.3 Measuring equipment A.2 Displacement Equipment for measuring the displacements at the head of the specimens using sensors shall be capable of –6 measuring by a static method to an accuracy of at least ±1. for which the dimensions are given in Table A.2. Figure A.3.1.1.3 Specimen preparation A.3.1 — Dimensions of the specimens Dimensions of the Type of mixture specimens D ≤ 14 mm 14 < D ≤ 20 mm 20 < D ≤ 40 mm B 56 ± 1 mm 70 ± 1 mm 70 ± 1 mm b 25 ± 1 mm 25 ± 1 mm 25 ± 1 mm e 25 ± 1 mm 25 ± 1 mm 50 ± 1 mm h 250 ± 1 mm 250 ± 1 mm 250 ± 1 mm A.2 The specimens subject to the test shall be obtained. by sawing.EN 12697-24:2004 (E) A.3. from slabs taken from road layers or from cores with a minimum diameter of 24 .2 — Geometry of the specimens Table A.

2 Characteristics of the specimens The specimens shall be measured to an accuracy of 0. EN 12697-24:2004 (E) 200 mm taken from road layers. The embedding check shall be carried out using a specimen made of aluminium alloy type EN AW 2017T4 with a rectangular section (13. A. An example of the equipment is shown Figure A.1 mm.3 — Example of aluminium alloy specimen 25 . The standard deviation on vi % shall be ≤0.5 ± 1) mm × (30 ± 1) mm and a minimal length of 220 mm (an example is shown in Figure A.3 The specimens shall be stored on a flat surface protected from the sun at a temperature of <30 °C in conditions that prevent distortion.3 Embedding Check The specimens shall be embedded following a procedure that complies with the embedding check procedure.3. The displacement and the strain shall be recorded.1) and shall have a thickness of not less than 40 mm. A force shall be applied on the top of the specimen so that the measured strain is equal to the strain recorded on the test machine to ±1 %. A. A. The metal specimen shall be fixed on the test machine.7 %. NOTE Other procedures may be used if there are able to give the same results.4.1.3. The displacement shall not differ from more than 5 %.3. The metal specimen shall be fixed on an L-shape frame made of steel of more than 80 mm × 80 mm section.3). A force of about 200 N shall be applied on the top. The slabs shall be of adequate dimensions (see Table A. Dimensions in millimetres Figure A.

Alternative fitting procedures may be used provided it can be shown that no movements take place at the base of the sample. 26 . as shown in Figure A.5 Gluing the ends Before fitting to the test machines.4 — Example of equipment for embedment procedure verification A. Glue film shall be as thin as possible. each specimen shall be glued by its large base in the groove (about 2 mm deep) of a metal base having a minimum thickness of 20 mm. NOTE A cap glued to the head of the specimen allows the displacement to be applied.3. A.3.5. This operation shall be carried out on a gluing rig allowing the positioning of the specimen on the base to be ensured.4 Stabilisation of the specimens The specimens shall be tested after between 2 weeks and 8 weeks from the date of cutting.EN 12697-24:2004 (E) Key 1 Screw to apply the deformation 4 Measured strain 2 Displacement measurement 5 Recorded strain 3 Support 6 Recorded stress Figure A.

2 The specimen to be tested shall then be installed on the test machine.1 The thermostatic chamber and the loading equipment shall be brought to the test temperature.1) Ki A. The fatigue test shall not be started until it has been verified that the test temperature has been achieved in the specimen (if necessary using a dummy specimen).4.4.1.4.1 Preparing the test equipment A. the desired head displacement shall be calculated using the following equation: εi zi = (A. NOTE The average reaction force between 100 cycles and 500 cycles is defined as the initial value of the reaction force. The adjustment of the displacement shall be ±5 µm. The number of cycles Ni at the failure criterion shall be measured with an accuracy of 300 cycles. The displacement zi shall be measured and εi calculated for this element test.4.3.5 — Fixation of the specimen A. or 27 .3 Choice of the strain A.4. EN 12697-24:2004 (E) Key 1 Groove of approximately 2 mm 2 Metal base Figure A. If a metallic specimen is used to adjust the displacement.1. NOTE The specimens should not have been pre-stressed in any way because that could modify the results.2.1. For each specimen i. it shall be the same type as the metallic specimen described in A. A.1 The deformations εi shall be selected so that either  the values are approximately regularly spaced on a logarithmic scale.4. Between 100 cycles and 500 cycles.2 Carrying out the fatigue test The specimen i shall be moved sinusoidally at its head at the imposed displacement amplitude ±5 µm until the failure criterion has been reached.4 Procedure A. the reaction forces shall be recorded to ±2 % and the average reaction force calculated. A.

6 in which the axes are the reverse of the way that they are often shown so that the slope is consistent with that defined for the test. The average values shall be approximately regularly spaced on a logarithmic scale.4.5 Calculation and expression of results A. A.EN 12697-24:2004 (E)  there are at least 3 levels of deformation. A. A.1 On the basis of the results representing the length of life Ni for εi chosen.2 The deformations shall be such as at least one third of the element tests provide results with 6 6 N ≤ 10 and at least one third of the element tests provide results with N ≥ 10 . the fatigue line shall be drawn by making a linear regression between the decimal logarithms of Ni and the decimal logarithms of εi having the following shape:  1 lg ( N ) = a +   × lg (ε ) (A. 28 . When this is not the case. with a homogeneous number of specimens (to 1 or 2 specimens) at each level. NOTE An example of a fatigue line is shown in Figure A.3. additional element tests shall be carried out.4 Number of element tests At least 18 element tests shall be used to determine the result.4.5.2) b with correlation coefficient r2.

5 ε 6 × (10 −2b×S0 − 10 2b×S0 ) (A.5.6)  + 6  S0 = S N n 2   ( n − 1) × S lg( ε)  29 .5) where  1 (lg( ε ) − lg( ε ) )2  (A.2 For n results. EN 12697-24:2004 (E) Key Y log (N) X log (ε/10 000) N Number of load cycles ε Strain Figure A.4) ( n − 2)  the quality index ∆ε6 ∆ε 6 = 0.3)  the estimation of the residual standard deviation SN (1 − r22 ) × ( n − 1) S N = S lg(N) × (A.6 — Example of fatigue line A. the following shall be calculated: 6  the estimation of the strain at 10 cycles ε 6 = 10 b×(6 − a) (A.

σr = 0. standard deviation. d) the estimation of the residual standard deviation sN. σr = 1. r = 4.  reproducibility. A. limit 95 %. have been determined according ISO 5725-2 with 11 laboratories (3 European countries). The experiment was on asphalt concrete AC14 at 10 °C and 25 Hz in 2001.3 Results relating to l/b:  repeatability.  repeatability.. standard deviation.7.6 Test report The test report shall refer to the items listed in clause 7 together with: a) ε6.060 2.  repeatability. A. limit 95 %.7.2 µstrain. σR = 1.43 µstrain. r = 0.  reproducibility. using different equipment.1 General Reproducibility and repeatability of the two-point test method on isosceles specimens.2 Results relating to ε6:  repeatability.  reproducibility. e) correlation coefficient r2.3 µstrain. σR = 0.7 Precision A.021 3. c) the slope l/b. A. standard deviation. limit 95 %. R = 8. NOTE 1 test result comprises measurements on not less than 18 individual specimens. limit 95 %.EN 12697-24:2004 (E) A. 30 .7. b) ∆ε6.  reproducibility. standard deviation.43 µstrain.022 7. R = 0.064 2.

it should be included in the test report.1 °C. NOTE If a frequency other than 25 Hz is used. EN 12697-24:2004 (E) Annex B (normative) Two-point bending test on prismatic shaped specimens B.3.3. The test machine shall be capable of applying the displacement to specimens at a frequency of (25 ± 1) Hz and.2 Equipment B.2 Thermostatic chamber The thermostatic chamber shall be ventilated and capable of allowing the temperature of the metal base of the specimens and the average temperature of the air draught at tens of millimetres from the specimens to be fixed with an accuracy of ±1 °C throughout the duration of the test. If the test machine is entirely contained within the thermostatic chamber.2. There shall be a system for logging the displacements measured. on specimens prepared in a laboratory or obtained from road layers with a thickness of at least 40 mm. B.1 Principle This annex describes a method to characterise the behaviour of bituminous mixtures under fatigue loading by 2-point bending using square-prismatic shaped specimens.2.2. B.1 µm/N during the test.2. 31 . There shall be a system for logging the forces measured. Results derived from tests at different frequencies are not directly comparable.3 Temperature Measuring probes for measuring the temperature of the metal base plate of the specimen shall have an accuracy of 0.1 Test machine The test machine shall consist of a system enabling to apply a sinusoidal displacement to the head of the specimen with a fixed frequency. The chamber shall be calibrated to an accuracy of 0. the temperature of the metal base of the specimens shall satisfy the conditions relating to the air draught. This temperature shall then be recorded instead of the air temperature.1 Force Equipment for measuring force shall determine the force at the head of the specimens from the electrical current consumption of the electro-dynamic swinger used to an accuracy of ±1 N.2 Displacement Equipment for measuring the displacements at the head of the specimens using sensors shall be capable of –3 measuring to an accuracy of at least ±10 m. There shall be a system for logging the temperatures measured. B.2. at other frequencies ±4 %. B. if required for special purposes. The displacement shall vary less than 0.3.5 °C.3 Measuring equipment B. The method can be used for bituminous mixtures with maximum aggregate size of 20 mm. B.2.

3 Specimen preparation B.4.2 Characteristics of the specimens The specimens shall be measured to an accuracy of 0. The longitudinal axis of the slab shall be parallel with the axis of compaction.3. from slabs made in laboratory according to EN 12967-33.3.EN 12697-24:2004 (E) B. B.1 mm. The fatigue shall not be started until after a minimum of 1 h for temperature stabilisation or after verification that the test temperature is achieved in the specimen (if necessary using a dummy specimen).5 %. The power supply for the electrodynamic swinger shall be adjusted by the calibration line for the intended displacement at the head.3. The standard deviation on vi % shall be ≤0.1 Sawing and storing The specimens shall be of square column shape of the dimensions given in Table B. the applied displacement at the head per level of tension shall be the same at all levels of tension. from slabs of a minimal thickness of 40 mm or from cores with a minimum diameter of 200 mm taken from road layers. The specimens shall be obtained by sawing. Table B. B.4 Gluing the ends During fitting to the test machines.1 Preparing the test equipment The thermostatic chamber and the loading equipment shall be brought to the test temperature. NOTE A cap glued to the head of the specimen allows the displacement to be applied. The specimens shall be stored on a flat surface protected from the sun at a temperature of (20 ± 2) °C in conditions that prevent distortion.3. B.1 — Dimensions of the specimen (B) Dimensions of the Type of mixture specimens mm D ≤ 22 mm D > 22 mm b 40 ± 1 80 ± 1 e 40 ± 1 80 ± 1 h 160 ± 1 320 ± 1 B.4 Procedure B. If the coefficient of variation of the geometry of the specimen is Kσi ≤ 1 %. each specimen shall be attached with its upper face on the metal plate of the test machine having a minimum thickness of 20 mm. 32 .3 Stabilisation of the specimens The specimens shall be tested after between 2 weeks and 8 weeks from the date of cutting.1.

2 The following properties shall be calculated:  estimation of Aσ0. Aε0. designated as Âσ 0 . 33 . Kσi is the constant for consideration of the geometry at constant strength.5.1) Kσ i where Pij is the amplitude of the strength applied to the head. and between 10 and 10 for at least one level. level of tension σj max.1 On the basis of the results representing the length of life. NOTE 1 This amplitude corresponds with the intended tension and is given by the following equation: σ j max Pij = (B.4.5 Calculation and expression of results B. corresponding to the strength applied to the head. Aε1. B. the fatigue line shall be drawn by making a linear regression between the natural logarithms of σj max having the following shape: ln ( N ij ) = A0 + A1 × ln (σ j max ) (B.  correlation coefficient of the regression rσ . The 4 levels of tension shall be chosen for the material so that the average fatigue life of the series lies between 10 6 6 7 and 10 cycles for a minimum of 2 of them. designated as Âσ 1 .4. Nij. B.4. B. Aσ0 are the parts of axes of fatigue line at constant strength. NOTE 2 The initial value of the displacement is defined as abscissa of the linear regression of the linear part of the line that is obtained when the displacement is adjusted to the cycles. Aσ1 are the slope of fatigue line at constant strength.2 Carrying out the fatigue test B.5.2. EN 12697-24:2004 (E) B.2) where Nij is the length of life of the specimen i at level of tension σj max.4.  estimation of Aσ1.2 The test shall be stopped when the amplitude of the displacement is greater than 280 µm. σj max the greatest relative tension of the specimen. B. in Newtons (N).1 The head of the specimen shall be moved sinusoidally with the intended displacement amplitude.2.3 Choice of the tension The test shall be carried out at not less than 3 levels of tension with a minimum of 6 repetitions per level.

7) j = 1 i = 1 N −1  where σj max is the greatest relative tension of the specimen.4)  confidence interval of 95 % of σ̂ 6 designated as ∆σˆ 6 ∆σˆ 6 = σˆ 6 ×  − 1 + e − 2 pσ × sσ 0  (B. corresponding to the strength applied to the head. rε. N is the number of element tests. 6  estimation of the tension at 10 cycles − Aσ 0 + ln(10 6 ) Aσ 1 σˆ 6 = e (B. 34 . designated as sσ x y sσ x/ y = s N × (1 − rσ )× (N − 1) 2 (B. N is the number of element tests.EN 12697-24:2004 (E)  slope pσ = 1 Aˆ σ 1 .6) N (N − 1)× sσ2 where σ̂ 6 is the tension. σ is the tension at a middle point.  the estimation of the standard deviation of σj max is 2 l n  ln(σ j max ) − ln(σ )  sσ = ∑ ∑    (B.5)   with 1 (ln(σˆ 6 ) − ln(σ ) ) 2 sσ 0 = sσ x/y × + (B. sσ is the estimation of the standard deviation of σj max.3) N −2 where sN is the estimation of the standard deviation of Nij.  estimation of the standard deviation σ σ x y . σ is the tension at a middle point. rσ are the correlation coefficient of the regression. corresponding to 106 cycles.

corresponding to the strength applied to the head. l is the number the level of tensions σj max. B. n is the number of specimens at the level of tension σj max.8) where σj max is the greatest relative tension of the specimen. b) average number of cycles and the standard deviation obtained for each level of tension.  the tension at a middle point is l n ln(σ j max ) ∑ ∑ N σ = e j =1 i =1 (B. N is the number of element tests. d) confidence interval of σ̂ 6 for a probability of 95 %. EN 12697-24:2004 (E) l is the number of tension levels σj max. 35 .6 Test report The test report shall refer to the items listed in clause 7 together with: a) choice of test strength controlled. c) tension corresponding with 10 cycles 6 σ̂ 6 . n is the number of specimens at the level of tension σj max.  s N is the estimation of the standard deviation of ln(Ni) 2 l n   l n ln( N ij )  ∑ ∑ ln( N ij ) −  ∑ ∑    j = 1 i = 1 N  j =1 i =1  sN = (B. e) slope p. l is the number of tension levels σj max. N is the number of element tests. N is the number of element tests.9) N −1 where Nij is the length of life of the specimen i at level of tension σj max. n is the number of specimens at tension levels σj max.

B. 36 .EN 12697-24:2004 (E) f) estimation of the residual standard deviation sx/y. NOTE 1 test result comprises measurements on not less than 18 individual specimens.7 Precision The precision of this test has not yet been established.

EN 12697-24:2004 (E) Annex C (normative) Three-point bending test on prismatic shaped specimens C.2 Equipment C.1. C.0 mm and a reading accuracy of better than ±5. 37 .0 µm.1 Principle C.3 Extensometer and displacement sensor Extensometer.2 Element test An element test shall consist of applying a constant amplitude sinusoidal displacement to the mid-span point of a beam shaped specimen supported at both of its ends.5 kN.3 Fatigue line Element tests shall be carried out on specimens drawn from a homogenous group at different displacement amplitudes. a measuring range of between ±0.5 mm and a reading accuracy of better than ±0. shall have a measuring base of 50 ± 0. used to measure the strain at the mid-span section of the specimen.2. C.1. C. C. the strain at the mid-span section of the specimen shall be recorded regularly against the number of cycles. The sensor that measures the displacement of the piston rod that applies the load shall have a displacement range greater than or equal to ±2.1.2. For a given frequency of sinusoidal displacement. with a reading accuracy of ±0.002 kN over a measuring range of ±2.2 mm and ±0.025 µm.5 mm. used to measure the dynamic load.2 Load cell Load cell. The result shall be obtained from the correlation of the maximum initial strain at the mid-span section of the specimen. C. Throughout the element test. the method shall be carried out on several elements tested at a controlled temperature. and the number of cycles needed to reduce to a half the initial stiffness of the specimen. with controlled displacement by three point bending using prismatic beam shaped specimens. A fatigue line of the mixture under test shall be drawn by approximation of the results of the element tests. The method can be used for bituminous mixture specimens with maximum aggregate size of 22 mm or for samples from road layers with a thickness of at least 50 mm.2.1 General This method characterises the behaviour of bituminous mixes under fatigue loading. The behaviour is characterised through the determination of the fatigue law in terms of strain (relation between strain and number of load cycles at failure) and the associated energy law.1 Test machine Any kind of servo-hydraulic control press capable of generating sinusoidal cyclic loading of the required frequency and amplitude.

a correction procedure for the back-calculation software is permitted.5 Data acquisition equipment An automatic data acquisition system that shall consist of a computer and an analogue/digital conversion board. a reference material with a phase lag unequal to zero is preferred but a material like aluminium (E around 72 GPa.6 Thermostatic chamber A chamber containing the specimen and clamping devices that shall be capable of maintaining a constant temperature of (20 ± 1) °C. 38 . If. C.I) of the beam(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. The reference beam shall be tested at not less than 2 frequencies. 2 temperatures and 2 deflection levels. systematic deviations (or larger deviations) are observed.2. C. The bending moment (E.5 for the phase lag (see C.5 for the known phase lag. If possible.3.2.2. phase lag is zero) is also acceptable. The back-calculated stiffness moduli shall be within 2 % with respect o to the known modulus and within 0.8).2. C.3.7 Other general equipment Trays. C. C. C. NOTE The geometry of the reference beam should be selected so that it will lead to a weight comparable with the weight of an asphalt beam. scales and thermometers.EN 12697-24:2004 (E) C.4 Clamping device A device capable of clamping a specimen (beam) in the bending frame in order to provide horizontal translation and rotation freedom at all supports.3. due to the electronic components or mechanical equipment.1 Manufacturing and sawing The test beam specimens shall be obtained from samples manufactured in accordance with EN 12967-33. They shall be tested after between 2 weeks and 8 weeks from the date of cutting.2.8 Check on the operation of the complete equipment and the mounting of the specimen The complete equipment shall be tested at least once a year with at least one reference beam with a known stiffness modulus (modulus and phase lag). At least 10 test beams of the same mixture shall be manufactured in order to obtain the fatigue law of the material.3 Storing The specimen shall be stored on a flat surface at a temperature of (20 ± 1) °C.3 Specimen preparation C. C. The dimensions of the test beams shall be (300 ± 10) mm × (50 ± 3) mm × (50 ± 3) mm. The clamping of the reference beam should be equal to the procedure for an asphalt beam. The board shall be capable of generating a record of both the load and extensometer signal functions and shall have a resolution such that the error due to the signal conversion process shall be equal to or smaller than the reading accuracy of the load cell and the extensometer.2. The back-calculated stiffness modulus for a reference beam ° with a known stiffness modulus shall be within 2 % for the modulus and within 0.2 Bulk density The bulk density of the specimens shall be determined in accordance with EN 12697-6.

NOTE The ability to move and tilt is necessary in order to prevent the specimen from being stressed due to bending or torque efforts originated during the process.1.4. in seconds (s).1.2 The load. The reading frequency for each function shall be greater than 50F where F is the frequency of the applied displacement wave. 2D0 is the total amplitude of displacement function.3. starting at cycle 200. 39 . The first piece of tube shall be glued to one of the sawn faces of the specimen so as to be equidistant from both ends.3.2 Carrying out the fatigue test Once the specimen and extensometer have been assembled and brought to the test temperature.4 Procedure C. Two other tube sections shall be glued to the opposite sawn face.4.1 The specimen shall be clamped to the support mechanism through the two metallic tubes glued to one of its faces and to the piston rod through the tube glued to the opposite face. C. In order to clamp the test beam to the support mechanism (C. stresses that can modify the behaviour during the test. in Hertz (Hz).1 The functions shall be recorded every 500 cycles. and recorded during one whole cycle.4. 1 200.4.4 Clamping devices preparation The test beams shall have two opposite sawn sides of (300 ± 10) mm × (50 ± 3) mm.1) where DC is the displacement at instant t. Their position shall match the position of the simple supports described in A. f is the wave frequency. and the total amplitude 2D0 shall vary from test to test. a cyclic displacement of the piston rod shall be applied according to the following sinusoidal function: DC = D0 × sin ( 2 × f × t) (C.4.4). NOTE The values of the total amplitude usually range from 80 µm to 350 µm.1) is reached. t is the time. C.4.2.2 The extensometer shall be fixed to the face of the beam where the two metallic tubes are glued and positioned at the geometric centre of such face. The support mechanism shall be capable of moving and tilting its axes. The thermostatic chamber and the loading equipment shall be brought to the test temperature. depending on the mixture. The wave frequency shall be 10 Hz. extensometer signal and displacement functions shall be defined at each cycle by at least 50 equally time gapped points.3.3 Load function.1.1. extensometer signal function. NOTE Hence the readings are triggered at cycles 200. C. in microns (µm). The loading shall continue until the conventional failure criterion (3. and displacement function recording C. EN 12697-24:2004 (E) C. The centre of each tube section shall be at the same distance from the centre of the tube section glued to the opposite face of the beam. C.1 Preparing the test equipment C. three pieces of square tubing shall be used. C.4. The tubes shall be clamped to both the supports and the piston rod by means of jacks or other suitable devices. in microns (µm).4. 1 700…. 700.

in megapascals (MPa). 40 .5. in millimetres (mm). in millimetres (mm). NOTE 2 Because the load and stain gauge signal functions are defined by more than 50 points per cycle. The test shall be finished when the amplitude of the cyclic load calculated at cycle N is half of the amplitude of the cyclic load calculated at cycle 200.1.5.4.1 The stress of the mixture shall be assessed by means of the stress at the mid-span point of the face of the test specimen where the two supports are placed.3) 2 B × L − B 2 − 400 where ε is the instant strain. in millimetres (mm).5.5 Calculation and expression of results C. NOTE The stress is normal to a plane perpendicular to the support face plane. The stress shall be determined for each cycle using the following equation: 3 ( L − 20) σ = P× (C. b is the width of specimen.EN 12697-24:2004 (E) C. C. in millimetres (mm). C.2 The strain of the specimen shall be assessed by means of the tensile strain at the same point where the stress is calculated.2) 2 (b × e 2 ) where σ is the instant stress. EXT is the instant extensometer signal. NOTE 1 The strain is normal to a plane perpendicular to the support face plane.1 Calculation of the stress function and the strain function at a cycle C. L is the distance between supports. The strain shall be determined at each cycle using the following equation: 2 EXT × ( L − 20) ε = (C. in millimetres (mm). the failure criterion.1. in megapascals (MPa). B is the measuring base of the extensometer.4 End of test The amplitude of the dynamic load shall be calculated after the previous cycle and prior to the following cycle as the difference between the maximum and minimum values of the load recorded during the cycle being considered. L is the distance between supports. P is the instant load. e is the thickness of specimen. in millimetres (mm). the stress and strain functions is defined by more than 50 points per cycle.

EN 12697-24:2004 (E) C.7) π where Φ is the phase difference angle in degrees.5. and density of dissipated energy at one cycle C.2 Calculation of the dynamic modulus.4) εc MD is the dynamic modulus. Kt. in megapascals (MPa). σc is the cyclic amplitude of stress. in radians (rad).6) where σa is the approximate stress function value. in megapascals (MPa). Kε are constants. F is the frequency of the load wave. 41 . Βε is the phase angle of the approximate strain function. εa is the approximate strain function value. phase difference angle. C.2.2. in megapascals (MPa).5. εc is the cyclic amplitude of strain.1 The dynamic modulus shall be determined at each cycle using the following equation: σc MD = (C. 2At is the amplitude of the approximate stress function. NOTE The phase angle is defined as the existing phase difference between the stress and the strain.3 The phase difference angle shall be determined using the following equation: 180 Φ = ( Bε − B t ) × (C.2 The phase difference between the stress function and the strain function shall be determined through a least square approximation for both the stress and the strain (defined by more than 50 equally time spaced points) according to the following equations: ( ) σ a = At × sin 2π × F × t + B t + K t (C. Bt is the phase angle of the approximate stress function.5) ( ) ε a = Aε × sin 2π × F × t + Bε + K ε (C. in ten Hertz (10 Hz). The cyclic amplitude of a function at a cycle is the absolute value of the difference between its maximum and minimum value during that cycle.5.2. in megapascals (MPa). C. in radians (rad). NOTE The dynamic modulus at a cycle is defined as the quotient of the cyclic amplitude of the stress over the cyclic amplitude of the strain.5. 2At is the amplitude of the approximate strain function.

5. in megapascals (MPa) or megajoules per cubic metre (MJ/m ).5.EN 12697-24:2004 (E) C.5 The cyclic amplitude of displacement shall be determined in the same way as the stress and strain cycle amplitudes.11) ε 6 = k1 × 10 6 k 2 (C. according to the following equations: ε = k1 × N k 2 (C.2.5. NOTE The density of dissipated energy results from the asphalt mixture at the point where the stress and the strain are calculated.2.25π (C. N is the number of cycle at end of test. m is (N – 200)/500.3 Determination of the fatigue law and energy law The controlled displacement fatigue law and the energy law shall be determined from the results of not less than 10 element tests.2. W is the total density of dissipated energy throughout the whole test.4 The density of dissipated energy shall be determined using the calculated cyclic amplitude of the stress and the strain and the phase difference angle using the equation: DDE = Tc × ε c × sin(φ ) × 0. in megajoules per cubic 3 metre (MJ/m ). 42 . 3 DDE (x) is the density of dissipated energy at cycle x. in megajoules per cubic metre (MJ/m ).12) where ε6 6 is the strain at 10 cycles.10) k W = k3 × N 4 (C.5. ε is the half cyclic amplitude of strain function at cycle 200. C. N is the total number of cycles.8) where 3 DDE is the density of dissipated energy. in megajoules per cubic metre 3 (MJ/m ). and shall remain constant throughout the test. The fatigue law and energy law shall be obtained through least square approximation of the set of coupled values. C. C.6 The total density of dissipated energy throughout the whole test shall be calculated from the density of dissipated energy at each one of the recorded cycles using the following approximate equation: m DDE (total ) = 200 DDE (200) + 500 ∑ [ DDE (200 + 500i )] (C.9) i =1 where DE(total) is the total density of dissipated energy throughout the whole test.

 cyclic amplitude of strain function. C. d) details of each element test:  dimensions of the beam shaped specimen (width and thickness at midsection. k4 is adimensional). The energy law is defined using coupled values of the total density of dissipated energy throughout the test [DDE(total)] and the total number of cycles. b) energy law constants.  cyclic amplitude of stress function. b.  dynamic modulus.  relative densities.  measuring base of the extensometer.  for each cycle:  cyclic amplitude of central displacement.7 Precision The precision of this test has not yet been established. 3  density of dissipated energy.  total energy of dissipated energy throughout the test.6 Test report The test report shall refer to the items listed in clause 7 together with: a) fatigue law constants. 3 k3.  cyclic amplitude of central displacement. N.  phase difference angle. 43 . 6 c) strain for 10 cycles. J/m . EN 12697-24:2004 (E) k1. NOTE 1 test result comprises measurements on not less than 18 individual specimens. Mpa. µm. d. k4 are coefficients of the energy fatigue law (k3 in megajoules per cubic metre (MJ/m ). NOTE The fatigue law is defined using coupled values of the half cyclic amplitude of the strain at cycle 200 [1/2 εc (200)] and the total number of cycles. c. C.  total number of cycles to failure the operating conditions. a. k2 are coefficients of the strain fatigue law. length).

This load configuration shall create a constant moment. The influence of 3) can only be determined by calibration measurements using an elastic material with a known Young’s modulus. Using these measurements.1. the influence can be ignored because the test frequency is far below the first resonance frequency of the system and a zero value for T can therefore be adopted.1. The prismatic beam shall be subjected to four-point periodic bending with free rotation and translation at all load and reaction points. The applied force. The applied load shall vary sinusoidally.). the measured deflection and the (system) phase lag between force and deflection shall be recorded. Constant and equal loads shall be applied at the two inner clamps. the coefficient for the system losses is denoted by T. The vertical position of the end-bearings (outer clamps) shall be fixed.2 Element test For each element test. The bending shall be realised by loading the two inner load points (inner clamps). the deflection and the phase lag between these two signals shall be measured as a function of time. NOTE 3 The dissipated energy per cycle can be split up into three parts: 1) Viscous Energy Dissipation in the beam due to bending. NOTE 1 The width B and height H of the specimen should be at least three times larger than the maximum aggregate size D. the load required to bend the specimen. Several element tests shall be carried out in a ventilated atmosphere with a controlled temperature for a given frequency f0 of sinusoidal load applications. D. the test will not be strictly in accordance with this annex and this non-compliance should be explicitly mentioned in the report. The exact value for T has to be derived from the calibration stiffness measurements.1 Principle D. and hence a constant strain. the effective length between the outer clamps L should be at least six times the maximum value for B and/or H. particularly if the test frequency ω0 is close to the first resonance frequency of the test equipment. 44 . between the two inner clamps.EN 12697-24:2004 (E) Annex D (normative) Four-point bending test on prismatic shaped specimens D.1 General This annex describes a method to characterise the behaviour of bituminous mixtures under fatigue loading in a four-point-bending test equipment of which the inner and outer clamps are symmetrically placed and using slender rectangular shaped specimens (prismatic beams). During the test. perpendicular to the longitudinal axis of the beam. The fatigue life of the test specimen shall be determined according to the chosen failure condition. in the vertical direction. 2) is much smaller than 1) and can be ignored in the interpretation. NOTE 2 Technical limitations of the apparatus in combination with the maximum grain size in the asphalt mixture can make it difficult to comply the requirements as to the ratios B/D and/or H/D. In the interpretation equations. In order to ensure the slenderness of the beam. If either of these requirements are not met. In general. However. the fatigue characteristics of the material tested shall be determined. 3) can play a role in the interpretation of the data. 2) Fatigue damage (creation of micro defects etc. NOTE The principal concepts of an element test are shown in Figure D. two inner and two outer clamps shall be symmetrical located with respect to the centre of the prismatic specimen Ltot/2.1. 3) System losses (damping).

e.  estimation of the standard deviation of the residual dispersion of the natural logarithms of fatigue lives Sx/y. The tests shall be repeated at different levels with respect to the chosen loading test condition (i. EN 12697-24:2004 (E) Key 1 Applied load 5 Deflection 2 Reaction 6 Return to original position 3 Specimen 7 Free translation and rotation 4 Specimen clamp Figure D.3 Fatigue line Specimens shall be drawn from a homogeneous group for repeated element tests at the same test condition. different deflection levels in the case of the constant deflection mode or different force levels in the case of the constant force mode).1 — Basic principals of 4-point bending D. The confidence interval relative to Q: ∆Q.  slope of the fatigue line plotted in log-log space p. temperature and loading mode) and the following values shall be calculated as follows: 6  level.1. 45 . The fatigue line of the mixture shall be drawn under the chosen test condition (set of frequency. of the loading mode test condition corresponding to 10 cycles for the fatigue life according to the chosen failure criteria k. Q.

3 Thermostatic chamber Thermostatic chamber which shall be ventilated and enable the average temperature of the air draught at least 10 mm from the specimens to be fixed with an accuracy of ±1 °C (throughout the duration of the test).1) Z ( A) R ( L / 2) 4 A × (3 L − 4 A) A should be chosen in the interval 0. If A/L is chosen outside this interval.1). NOTE 4 The deflection should be measured at the diagonal centre of the top or bottom surface. D. NOTE 1 The resonance frequency of the load cell and the coupled moving mass should be at least 10 times as high as the test frequency. In order to check the required pure bending of the specimen. The assumed pure bending between the two inner clamps shall be checked by measuring the deflections at the inner clamp.2. the equations given in this annex are no longer applicable without introducing substantial errors. 46 .2 Clamping device A device capable of clamping a specimen (beam) in the bending frame in order to provide horizontal translation and rotation freedom at all supports.1 Electronic data registration equipment in which the transducer signals shall be amplified by low- noise amplifiers.2. the ratio will be 1. and in the middle of the specimen.5° for the phase lag (see D. x = L/2. f0.1 Hz. The measurement of the force shall take place midway between the two inner clamps. ° Regulation shall be to an accuracy of 0.4.1 Test machine Equipment that shall be capable of applying a sinusoidal load to a specimen by a suitable mechanism via two inner clamps mounted on the specimen (Figure D. The measurement of the displacement shall take place at the top surface or the bottom surface of the specimen between or at one of the two inner clamps. The outer and inner clamps shall be designed to permit rotation freedom and horizontal movements of the specimen within the clamps. NOTE 3 The resonant frequency of the transducer and the coupled moving mass should be at least 10 times as high as the test frequency.4 but preferably close to one third of the effective length L (ASTM configuration).5 C. the deflections of the two inner clamps should also be measured.5). The equipment shall be constructed of corrosion-resistant metal.2.2. The testing system shall be provided with a system to control the loading mode of the specimen in such a way as to meet the requirements for the execution of the test.2. shall be in the range 0 to 60 Hz with an accuracy of 0.EN 12697-24:2004 (E) D.2.0 mm and should comply with the specification for transducers of accuracy class 0.2 Equipment D. The back-calculated stiffness modulus for a reference beam with a known stiffness modulus shall be within 2 % for the modulus and within 0.2. D. The frequency of the load. D.25 < A/L < 0. NOTE The ratio of the amplitudes of the centre deflection and the deflection at the inner clamps should be a constant that is defined as: Z ( L / 2) R( A) 3 L2 − 4 A 2 = = (D.2. preferable in such a way that a value of 10 V or ±10 V corresponds to the full-scale deflection of the measuring range of the transducer concerned.4 Electronic data registration equipment D. NOTE 2 The displacement transducer should have a measuring range of ±1. The load cell shall have a measuring range of at least ±2 000 N and shall comply with the specifications for transducers of accuracy class 0. x = L/2.15. x = A. In that case.

2 Using analogue or digital measuring instruments. The length of the test specimen shall be calculated as the arithmetic mean of the length measurements. due to the electronic components or mechanical equipment. the values of the frequency components at the test frequency f0 shall be capable of being taken. The clamping of the reference beam should be equal to the procedure for an asphalt beam. 47 . D.1 mm at the places where the clamps are to be installed (x = 0. If possible.3 For the calculation of the strain.2.0 mm.1.2 The total length shall be measured four times with a ruler with an accuracy of 1. x = A.2. respectively.0 mm. and a direct measurement of the system phase lag between force and deflection.2.  difference between maximum and minimum measured value of the width and of the height shall not be greater than 1. 2 temperatures and 2 deflection levels.  angle between adjacent longitudinal surfaces shall not deviate from a right angle by more than 1°. The height and the width shall be measured with vernier callipers with an accuracy of 0.3.3 Specimen preparation D. the output of the amplifiers shall be displayed and recorded with an accuracy of 1 N for the force and 1 µm for the displacement. The back-calculated stiffness moduli shall be within 2 % with respect to the known modulus and within 0.  width B and the height H should be at least three times the maximum grain size D in the tested material. NOTE The geometry of the reference beam should be selected so that it will lead to a weight comparable with the weight of an asphalt beam. the difference between minimum and maximum measured value of the length shall not be greater than 2. The reference beam shall be tested at not less than 2 frequencies. a reference material with a phase lag unequal to zero is preferred but a material like aluminium (E around 72 GPa. The bending moment (E.I) of the beam(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. If.3. dynamic stiffness modulus and (material) phase lag. NOTE This procedure enables a check on the required single sinusoidal signals with the chosen frequency.5 Check on the operation of the complete equipment and the mounting of the specimen The complete equipment shall be tested at least once a year with at least one reference beam with a known stiffness modulus (modulus and phase lag). systematic deviations (or larger deviations) are observed.4. The output of this Fourier transform is a discrete frequency spectrum. a correction procedure for the back-calculation software is permitted.5° for the known phase lag. phase lag is zero) is also acceptable. D. NOTE A digital data sampling process in combination with a (fast) Fourier transform is recommended. D. Specimens not complying with the specimen requirements shall not be tested. D. stress.1. D.0 mm in the centre of the top and the bottom surfaces.1 The specimen shall have the shape of a prismatic beam with the following nominal proportions and tolerances:  total length Ltot shall not exceed the effective length L by more than 10 %. x = L – A. EN 12697-24:2004 (E) NOTE Output sockets should be provided for connecting data recording and/or processing instruments.3.4.1 Dimensions D. NOTE It is also recommended that:  effective length L should not be less than six times whatever the highest value is for the width B or the height H. x = L). The width and the height of the specimen shall be calculated similarly from the width measurements and the height measurements.

D.6 Mounting For the mounting system of the inner and outer clamps on the beam. A specimen shall be considered to be dry when two weighings performed at intervals of 24 h differ by less than 0. void content or the existence of large aggregate particles has to be noted. If any of these requirements are not met.5 Condition The specimen shall be inspected visually and striking externals concerning homogeneity. the acclimatisation shall not last longer than six hours.2). a system shall be used which realises the best possible rotation and translation freedom. D. The distance of the beam to the border of the slab shall be at least 20 mm. The slabs made in the laboratory shall have at least a thickness of the required height H plus 20 mm. The required bending of the beam shall be checked by measuring the deflection at two different places between the two inner clamps (see D.1 g. In order to prevent ageing and deformation of the specimen. 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. compaction. The longitudinal axis of the beam shall be parallel with the axis of compaction. D.1 Preparing the test equipment D.1. In principle. the locations where the masses act are at the inner clamp(s).3 Drying After sawing. NOTE The relative humidity in the storage room should not exceed 80 %.3. If the specimens have to be stored for more than 1 month. the temperature in the storage room shall be between 0 °C and 5 °C.3.4. B/D > 3 and H/D > 3. D. the test will not be strictly in accordance with this annex and this non-compliance should be explicitly mentioned in the report. Specimens shall not be stacked on top of each other.1. The support on which the specimen rests shall be flat and clean.EN 12697-24:2004 (E) NOTE Technical limitations of the apparatus in combination with the maximum grain size in the asphalt mixture can make it difficult to comply the requirements as to width B. the test specimen shall be dried to constant mass in air. In such cases. 48 .25 %. 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. at a relative air humidity of less than 80 % and at a temperature between 15 and 25 °C. D. D.1 The thermostatic chamber and the loading equipment shall be brought to the test temperature for not less than the time given in Table D.4. Specimens not considered for immediate testing shall be stored in a dry room at a temperature between 0 °C and 20 °C.2.2 Sawing The specimens subject to the test shall be obtained by sawing from slabs made in laboratory or taken from road layers. the beams shall be rotated over an angle of 90°.3.4 Procedure D.3. NOTE Normally. The dry mass shall be weighed with an accuracy of 0. moving frame. The beam shall be weighed as well as all the moving parts between the load cell and the beam (e. the width B of the beam shall not be able to meet the requirement and shall be reported.3. The beams shall be sawn from the middle.4 Storage The specimen shall be stored fully supported. the same procedure holds for beams sawn from slabs taken from road layers. The specimens shall be tested after between 2 weeks and 8 weeks from the date of cutting.g.

 Mclamps. the test shall be undertaken at not less than three levels in the chosen loading mode (e. D.4. 30 Hz and 60 Hz and subsequently again at 1 Hz). In order to avoid premature fatigue damage. 20 Hz. at least 200 repetitions shall be applied.2. displacement and phase lag after the hundredth cycle (n = 100). EN 12697-24:2004 (E) Table D.1. D.2 The initial value of the calculated modulus Smix shall be calculated from the measured values for force. a frequency spectrum of initial complex (stiffness) moduli at the chosen test temperature shall be obtained prior to the fatigue test. 49 . in order to check the pure bending mode. The fatigue test shall be continued until the calculated modulus Smix has dropped to half its initial value or until the specimen breaks. 1 Hz. the total number of applications for all frequencies together shall not exceed 3 000. At low temperatures (Θ ≤ 10 °C).1 The beam with the two outer and two inner clamps shall be mounted into the load frame.g. the mass of the whole beam whole beam without the masses of the mounted clamps.4. the masses of the two inner clamps. The force. there shall be a short rest period of about 10 min before the actual fatigue test starts. The levels for the chosen loading mode shall be chosen in such a way that the fatigue 4 6 lives are within the range 10 to 2 ×10 cycles.4.g.3 The equivalent mass Meq shall be calculated for use in the calculation of the stiffness modulus.4.e.1 — Minimum time required to bring specimens to test temperature Test temperature Time °C h 0 2 20 1 D. and the mass of the load frame between the load cell and the loading mechanism. The loading mode in this pre-test shall be constant deflection representative for a maximum bending strain amplitude of less than 50 µm/m.  Msensor. The chosen loading mode (i. 10 Hz. 5 Hz. NOTE The intention is make at least 100 measurements that are taken at regular intervals over the test duration (n = 100 to n = Nf.3 Choice of test conditions For a given temperature and frequency. NOTE The value of the equivalent mass depends on the distance xs where the sensor is placed.2. displacement and phase lag between force and displacement shall be recorded after 100 cycles and regularly thereafter. this mass shall be added to the mass of the clamps.2 Carrying out the fatigue test D. D. The beam shall then be moved sinusoidally at the chosen frequency f0 at the initial imposed displacement. three strain levels with the constant deflection mode) with a minimum of six repetitions per level. D.4. the mass of the moving parts of the sensor. If.3 If required.4.2. a second sensor is placed at one of the two inner clamps. At each frequency. The necessarily force shall be applied through the load frame connected to the two inner clamps. This pre-test shall consist of response measurements at a range of nominal frequencies (e. D.4.2 The different masses of the moving parts shall be calculated as follows:  Mbeam. 3 Hz. including the mass of any adhesive (if used).1. constant deflection or constant force) shall be ensured by a feedback of the measured force or displacement.50).

 cumulated dissipated energy up to cycle n(i). th D. j represents the chosen failure criteria. D.2 The fatigue lives shall be measured at least at three levels for the type of loading mode with at least six repetitions per level.k ) = A0 + A1 × ln (ε i ) (D.1 On the basis of the results representing the length of life Ni. j. k represents the set of test conditions. The relevant test results shall be tabulated and graphically presented related to the load cycle number n(i) at which they are measured.1 Using the obtained data of the force.2 In order to determine the initial values.4.4.  estimation of the residual standard deviation. the fatigue line shall be drawn by making a linear regression between the natural th logarithms of Ni.k for the chosen failure criteria j and the set of test conditions k. the relevant results shall be calculated using the equations given in 3.5 Calculation and expression of results D.  correlation coefficient of the regression r. the mean calculated values over this amount of cycles shall be defined to correspond with the first cycle in this sample.4. The chosen test frequency f0 shall be equal to one of the frequency components in the discrete frequency spectrum.4. If the digital data is sampled over an integer amount of cycles. th εi is the initial strain amplitude measured at the 100 load cycle. the dissipated energy shall be calculated using all the frequency components of the obtained discrete frequency spectrum (Parsival’s law).  stress amplitude.5. deflection and phase lag between these two signals measured at load cycles n(i). NOTE The following optional test results can also be calculated:  (material) phase lag.EN 12697-24:2004 (E) D. D.5.3 If a Fourier transform is used.4.j. noted sx/y. These test results are:  strain amplitude.j.  estimation of A0 noted as q. The following values shall be calculated:  estimation of A1 noted as the slope p. 50 .5.2) where i is the specimen number.  dissipated energy per cycle. D.k and the natural logarithms of the initial strain amplitude (strain amplitude at the 100 cycle) having the following shape: ln ( N i.4.4 Data processing D. the first load cycle number n(i) shall be the 100 load cycle. σx/y.4.  modulus of the complex modulus (dynamic stiffness modulus).

including the results of that test.7 Precision The precision of this test has not yet been established. b) average number of cycles and the standard deviation obtained for each level of the chosen loading mode. D. d) slope p of the fatigue line. e) individual measured data points. EN 12697-24:2004 (E) 6  estimation of the initial strain for the chosen failure criteria at which a fatigue life of 10 can be expected for the given set of test conditions.6 Test report The test report shall refer to the items listed in clause 7 together with: a) description of the check that the complete equipment and mounting of the specimen are working appropriately. NOTE 1 test result comprises measurements on not less than 18 individual specimens. 6 c) initial strain corresponding with a fatigue life of 10 cycles for the chosen failure criteria and set of test conditions. 51 . D.

2. Fracture life shall be defined as the total number of load applications before fracture of the specimen occurs. E. the testing temperature and character of the material. This loading develops a relatively uniform tensile stress perpendicular to the direction of the applied load and along the vertical diametral plane. A cylinder-shaped test specimen shall be exposed to repeated compressive loads with a haversine load signal through the vertical diametral plane.5 to 10 kN with an accuracy of 0.1 Principle This annex characterises the behaviour of bituminous mixtures under repeated load fatigue testing with a constant load mode using Indirect Tensile Test (ITT). E.25 %.2 Equipment E.2 Loading The loading system shall be capable of applying at least a load ranging from 0.11C from MTS Corporation have been found suitable.3 Displacement Sensor for measuring the displacements along the horizontal diametral plan. 52 .1 Test machine The testing machine shall be capable of applying repeated haversine load pulses with rest periods at a range of load levels. NOTE The maximum load capacity required depends on the size of the specimen.2.4 Thermostatic chamber The thermostatic chamber shall be capable of control over a temperature range from 2 °C to 20 °C and with an accuracy of at least ±1 °C.2.5 Recording and measuring system Recording and measuring devices for determining the compressive load and the horizontal deformations which shall be capable of measurement at a minimum frequency of 10 Hz.75 mm. capable of measuring to an accuracy of at least 1 µm within a measuring range of up to 3.EN 12697-24:2004 (E) Annex E (normative) Indirect tensile test on cylindrical shaped specimens E.2. which causes the specimen to fail by splitting along the central part of the vertical diameter. E. type 632. NOTE Two extensometers connected in series. A cylindrical specimen manufactured in a laboratory or cored from a road layer can be used in this test. E.2. E. The resulting horizontal deformation of the specimen shall be measured and an assumed Poisson's ratio shall be used to calculate the tensile strain at the centre of the specimen.

2) mm and (19. 53 . The upper strip shall be fixed to a beam mounted on ball bushing guided posts. respectively. Key 1 Load cell 2 Asphalt specimen 3 Extensometer 4 Deformation strips 5 Loading strips Figure E.6 Loading frame The loading frame (see Figure E.2) mm. EN 12697-24:2004 (E) E. keep the loading strips in the vertical plan and eliminate undesirable movement of the specimen during testing.2) with concave surfaces and rounded edges shall have a radius of curvature equal to the radius of the test specimen.1 Loading strips Loading strips (see Figure E. The upper platen (weighs 1 000 g) provides an additional static load on the specimen.1 — The loading device with loading and deformation strips and specimen in place E.2. NOTE The ball bushing guided posts centre the specimen.1) shall consist of two loading strips.7 ± 0. Loading strips for 100 mm and 150 mm diameter specimens shall have widths of (12.2.1 ± 0.6.

2 Deformation strips Two curved steel strips with a radius of curvature equal to the radius of the test specimen to which deformation transducers shall be fixed. It is recommended to have a set of strips with different lengths. an example of which is shown in Figure E. The strips shall be fixed on opposite sides of the horizontal diametral plan by either glue or springs (see Figures E. as well as assigning the position of the loading strips. NOTE The positioning rig helps positioning and gluing of the deformation strips. The steel strips shall be 2 mm thick.2. E.2 — Illustration of loading and deformation strips E.EN 12697-24:2004 (E) E. At each end of the strips.2). The transducers shall be arranged so that the variation of the horizontal diameter can be measured by the variation of the distance between the two strips from the average value of the two transducers.2.3 is suitable for both 100 mm and 150 mm diameter specimens and for the various lengths of the deformation strips.7 Positioning rig A rig. The rig illustrated in Figure E. there is a screw with a plastic nut for the zero adjustment of the deformation transducers. 10 mm wide and normally 80 mm long.3.8 Glue NOTE Quick hardening cyanoacrylate type glue has been found suitable. NOTE The length of the strips depends on the specimen thickness.2.1 and E. 54 . Side view Front view Key 1 Deformation strip 2 Loading strips 3 Extensometer 4 Asphalt specimen Figure E.6.

E.3 — Example of positioning rig for both 100 mm and 150 mm diameter specimens E.3. E.3 Position of the deformation and loading strips The deformation strips shall be positioned and glued (if springs are not used) at the opposite sides of the horizontal diametral plane using the positioning rig.4. EN 12697-27.3. EN 12697-24:2004 (E) Figure E.3 Specimen preparation E.2 and note).  test specimen drilled from laboratory-prepared slab of asphalt.3.  test specimen prepared from drilled core taken from the road.3.4 Conditioning The specimens shall be placed in the thermostatic chamber and exposed to the specified test temperature for at least 4 h prior to testing. The cylindrical specimens subject to the test shall be obtained in accordance with:  test specimen prepared in the laboratory by Gyrator compactor.2 Specimen dimensions The specimen shall have either  a thickness of at least 40 mm and a diameter of (100 ± 3) mm for a maximum aggregate size of 25 mm. E. EN 12697-31.1 Test specimen 10 to 18 specimens shall be prepared (see E. The dimensions of the specimens shall be measured accordance with EN 12697-29. EN 12697-31. or  a thickness of at least 60 mm and a diameter of (150 ± 3) mm for a maximum aggregate size of 38 mm. The positions of the loading strips shall be assigned at the vertical diametral plane. The age of the compacted mixes shall be at least one week. 55 .

5. E.2 The fracture life shall be determined as the total number of load applications that causes a complete fracture of the specimen.5.3 The specimen shall be positioned in the loading device so that the axis of the deformation strips is perpendicular to the axis of the loading strips.5).5.5) increases by a factor of two over its initial value. E.4. The fracture life is obvious from the relationship between log number of load applications and the total horizontal deformation (see Figure E.4 sec rest time. This definition has been shown to be in fair agreement with the definition based on complete fracture of the specimen.2 The specimens shall be tested at three levels of stress with at least three specimens at each level for laboratory-manufactured specimens and at least five specimens for cores from road.5.4.6).1 The procedure in E. 250 kPa has been found to be a practical stress level. 56 .4 The deformation transducers shall be mounted and adjusted by screws so that the total gauge length can be used.7 When obvious cracking is shown on the vertical axis. the load and horizontal deformation shall be monitored continually and recorded at the pre-selected intervals.4. NOTE In almost every case. E. E. the test shall be stopped.4. Experienced operators can choose a suitable stress level with regard to the stiffness of the tested material.2 to E.1 The test shall cover at least a strain level range of approximately 100 µε to 400 µε and the fatigue life 3 6 of tested material shall be in a range between 10 and 10 number of applications.4.1 sec loading time and 0.4 Procedure E.5. E. E.5 Calculation and reporting of results E.5. NOTE Cores taken from the road should be selected at random in order to be representative for test section (see also NOTE to E.4.6 shall be carried out for each specimen tested. If the deformation shown on the monitor during the first 10 applications is outside the strain range (100 to 400) µε.6 During the test.EN 12697-24:2004 (E) E.5 The test shall start at a loading amplitude of 250 kPa.4. E. the test shall be stopped immediately and the load level adjusted. NOTE Fracture life can also be defined as when the strain (see E. A repeated haversine load shall be applied with 0. E.

2)  Ω   4 + π ×ν − π  E. Ω is the specimen diameter. in Newtons (N). in millimetres (mm). T is the specimen thickness.3) Ω where σo is the tensile stress at specimen centre. EN 12697-24:2004 (E) Key Y Horizontal deformation in millimetres (mm) X Humber of load applications 1 Fracture life Figure E. 57 . then ∆H ε o = 2 . in megapascals (MPa).5.35.4 — Determinations of the fracture live of a specimen E.5. in millimetres (mm). P is the maximum load. ∆Η is the horizontal deformation. εo is the tensile strain in µε at the centre of the specimen.1) π ×t × Ω  2 ∆Η   1 + 3ν  εo =  ×   (E.3 The maximum tensile strain and stress (option) at the centre of the specimen shall be calculated with the following equations: 2P σo = (E. in millimetres (mm).1 (E.4 If ν = 0.

k.EN 12697-24:2004 (E) E. The initial strain value is calculated from the difference between the average of the total horizontal deformations of 5 load applications from 98 to 102 and the average of the minimum horizontal deformations of 5 load applications from 60 to 64. n are material constants.5)  εo  where Nf is the number of load applications.6 The fatigue criterion for an individual bituminous material shall be determined from the tested specimens.4) n  1  N f = k ×    (E.5. εo is the tensile strain in µε at the centre of the specimen. 2 NOTE Usually.6. lg( N f ) = k + n × lg(ε 0 ) (E. which is illustrated in Figure E. This procedure makes it easy to calculate the initial strain by computer from the data sheet for the specimen.5 — Definition of the total horizontal deformation E. Key Y Horizontal deformation X Time a Total horizontal deformation Figure E.5. NOTE The initial strain is calculated after the envelope of the deformation has been stabilised and the repeated deformation has become stable.5 The initial strain shall be calculated according to equation E.9. if the R is less than 0. The least-squares regression relationship shall be fitted to the data of the logarithm of the initial strain as an independent variable and the data of the logarithm of the fracture life as a dependent variable according to equations E. increase the number of test specimens.5. which normally occurs before 60 load applications.4 and E.3 from the total horizontal deformation at th the 100 load application. 58 .

EN 12697-24:2004 (E) E.5 × 10 loading cycles is 13 µε. R². NOTE 1 test result comprises measurements on not less than 18 individual specimens. b) the correlation coefficient.7 Precision 6 Based on testing cores the average of the 95 % confidence interval of the strain corresponding with 0. 59 .6 Test report The test report shall refer to the items listed in clause 7 together with: a) a graphical and mathematical presentation of the fatigue criterion. E.

Revue Générale des Routes No. NF P 98-261-1. Theory of the bending test. 2002. and A VERSTRAETEN. Delft. Delft. C. 2 Euroasphalt & Eurobitume Congress. 1998. DELORME. Dienst Weg-en Waterbouwkunde report P-DWW-96-008. L. Delft. 713 2001/03. S F. Test relating to pavement — Determination of the fatigue resistance of bituminous mixtures — Part 1: Two point flexural fatigue test with constant displacement on trapezoidal isosceles specimens. J-L. 60 . Netherlands. SAID. 1996. FRANCKEN. Fatigue testing on bituminous mixes — Results of the exactitude experiment. Part III: System losses. and J WAHLSTRÖM. J-F CORTE and J-L GOURDON. 2002. Exactitude experiments in tests relative to pavements. Theory of the bending test. Netherlands. Part I: General theory.EN 12697-24:2004 (E) Bibliography ISO 5725-2. Netherlands. Theory of the bending test. DE LA ROCHE. Interlaboratory test program on complex modulus and fatigue RILEM REPORT 17. Part II: Influences of 1) overhanging beam ends and 2) extra moving massess. Dienst Weg-en Waterbouwkunde report DWW-2002-084. Revue Générale des Routes n°713 2001/03. Dienst Weg-en Waterbouwkunde report DWW-2002-083. Barcelona 2000. Validation of Indirect Tensile Method for Fatigue Characteristics of nd Bituminous Mixes. Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method.