1、Designation: D7369 11Standard Test Method forDetermining the Resilient Modulus of Bituminous Mixturesby Indirect Tension Test1This standard is issued under the fixed designation D7369; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision
2、, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers procedures for preparing andtesting laboratory-fabricated or field-recovered cor
3、es of bitu-minous mixtures to determine resilient modulus values using arepeated-load indirect tension test.1.2 The values stated in SI units are regarded as thestandard. Values in parentheses are for informational use.1.3 A precision and bias statement for this standard has notbeen developed at thi
4、s time. Therefore, this standard should notbe used for acceptance or rejection of a material for purchasingpurposes.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate
5、 safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D3387 Test Method for Compaction and Shear Properties ofBituminous Mixtures by Means of the U.S. Corps ofEngineers Gyratory Testing Machine (GTM)D3666 Speci
6、fication for Minimum Requirements for Agen-cies Testing and Inspecting Road and Paving MaterialsD4013 Practice for Preparation of Test Specimens of Bitu-minous Mixtures by Means of Gyratory Shear CompactorD6925 Test Method for Preparation and Determination ofthe Relative Density of Hot Mix Asphalt (
7、HMA) Speci-mens by Means of the Superpave Gyratory CompactorD6926 Practice for Preparation of Bituminous SpecimensUsing Marshall ApparatusD6931 Test Method for Indirect Tensile (IDT) Strength ofBituminous Mixtures2.2 Other Document:NCHRP Project 1-28A, Research Results Digest Number285Laboratory Det
8、ermination of Resilient Modulus forFlexible Pavement Design, January 20043. Terminology3.1 Definitions:3.1.1 contact load (Pcontact), nthe vertical load placed onthe specimen to maintain a positive contact between theloading strip and the specimen. The contact load is 4 % of themaximum load (0.04 Pm
9、ax) and is not less than 22.2 N (5 lb),but not more than 89.0 N (20 lb).3.1.2 core, nan intact cylindrical specimen of pavementmaterial, which is removed from the pavement by drilling andsampling at the designated location. A core may consist of, orinclude, one, two, or more than two different layer
10、s.3.1.3 cyclic load (resilient vertical load, Pcyclic), nloadapplied to a specimen, which is directly used to calculateresilient modulus.Pcyclic5 Pmax Pcontact(1)3.1.4 haversine-shaped load form, nthe required loadpulse for the resilient modulus test. The load pulse is in theform (1-cos u)/2 with th
11、e cyclic load varying from the contactload (Pcontact) to the maximum load (Pmax).3.1.5 instantaneous resilient modulus, ndetermined fromthe deformation-time plots (both horizontal and vertical) asdescribed in Section 10.3.1.6 lift, nthat part of the pavement produced withsimilar material and placed
12、with similar equipment and tech-niques. The lift thickness is the thickness of the compactedbituminous mixture that is achieved with one pass of thelaydown machine and the subsequent compaction process andcan be equal to or less than the core thickness or length.3.1.7 maximum applied load (Pmax), nt
13、he maximum totalload applied to the sample, including the contact and cyclic(resilient) loads.Pmax5 Pcontact1 Pcyclic(2)1This test method is under the jurisdiction of ASTM Committee D04 on Roadand Paving Materials and is the direct responsibility of Subcommittee D04.26 onFundamental/Mechanistic Test
14、s.Current edition approved Dec. 1, 2011. Published January 2012. Originallypublished 2009 as D736909. DOI: 10.1520/D7369-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, r
15、efer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.8 test specimen, nthat part of the layer which is usedfor, or in, the specified test. The thickness of the test specim
16、encan be equal to or less than the layer thickness.3.1.9 total deformation, ndetermined from thedeformation-time plots (both horizontal and vertical) as de-scribed in Section 10.4. Summary of Test Method4.1 The repeated-load indirect tension resilient modulus testof bituminous mixtures is conducted
17、through repetitive appli-cations of compressive loads in a haversine waveform. Thecompressive load is applied along a vertical diametral plane ofa cylindrical specimen of asphalt concrete. The resultinghorizontal and vertical deformations of the specimen aremeasured. Values of resilient Poissons rat
18、io are calculatedusing recoverable vertical and horizontal deformations. Theresilient modulus values are subsequently calculated using thecalculated Poissons ratio. Two separate resilient modulusvalues are obtained. One, termed instantaneous resilient modu-lus, is calculated using the instantaneous
19、recoverable deforma-tion that occurs during the unloading portion of one load-unload cycle. The other, termed total resilient modulus, iscalculated using total recoverable deformation which includesboth the instantaneous recoverable and the time-dependentcontinuing recoverable deformation during the
20、 unload orrest-period portion of one cycle.5. Significance and Use5.1 Resilient modulus can be used in the evaluation ofmaterials quality and as input for pavement design, evaluationand analysis. With this method, the effects of temperature andload on resilient modulus can also be investigated.NOTE
21、1The quality of the results produced by this standard aredependent on the competence of the personnel performing the procedureand the capability, calibration, and maintenance of the equipment used.Agencies that meet the criteria of Practice D3666 are generally consideredcapable of competent and obje
22、ctive testing/sampling/inspection/etc. Usersof this standard are cautioned that compliance with D3666 alone does notcompletely assure reliable results. Reliable results depend on manyfactors; following the suggestions of D3666 or some similar acceptableguideline provides a means of evaluating and co
23、ntrolling some of thosefactors.6. Apparatus6.1 Testing MachineTesting machine shall be a top load-ing, closed loop, electro-hydraulic or pneumatic testing ma-chine with a function generator capable of applying ahaversine-shaped load pulse over a range of load durations,load levels, and rest periods.
24、6.2 Loading DeviceLoading device should be capable oftesting 101.6 or 152.4 mm (4 or 6 in.) diameter specimens ofheights up to 63.5 mm (2.5 in.). The device should be compactenough to be used within an environmental chamber. It shouldhave a fixed bottom loading plate and a moving upper loadingplate.
25、 The movement of the upper plate should be guided bytwo columns, one on each side of the specimen and equidistantfrom the loading axis and the loading strips, to ensure it hasminimal translational or rotational motion during loading of thespecimen. The guide columns shall have a near frictionlessbea
26、ring surface. The surface of the guide columns shall befrequently inspected for any grooves caused due to friction.Alignment of the device, within the loading system, shall beachieved so that such friction is limited. The upper plate shallbe rigid enough to prevent excessive or undue deflection duri
27、ngloading. A picture of the loading strip parts is presented in Fig.1. The loading strips shall be perpendicular to the lineconnecting the two guide columns.6.3 Temperature-Control SystemThe temperature-controlsystem should be capable of maintaining a temperature of 5 to45C (41 to 113F) 61.0C (62F).
28、 The system shall includea temperature-controlled cabinet large enough to house theloading device and space adequate to pre-condition at leastthree specimens at a time prior to testing, as described in 8.3.6.4 Measurement and Recording SystemThe measure-ment and recording system shall include sensor
29、s for measuringand simultaneously recording horizontal and vertical deforma-tions and loads. The system shall be capable of recordinghorizontal and vertical deformations in the range of 0.00038mm (0.000015 in.) of deformation. Load cells shall be accu-rately calibrated with a resolution of 8.9 N (2
30、lb) or better.6.4.1 Data AcquisitionThe measuring or recording de-vices must provide real-time deformation and should becapable of monitoring readings on tests conducted to 1 Hz.Computer monitoring systems are recommended. The dataacquisition system shall be capable of collecting 200 scans persecond
31、 (a scan includes all deformation and load values at agiven point of time). The capability to have real-time plots(simultaneous to the data collection by the computer monitor-ing system) shall also be provided to check the progress of thetest. If strip chart recorders are used without computer moni-
32、toring systems, the plotting scale shall be adjusted such thatthere is a balance between the scale reduction required as aresult of the pen reaction time and the scale amplificationneeded for purposes of accurate measurement of values from aplot. Actual load values, and not the intended load values,
33、 shallbe used for calculation purposes and so the data acquisitionsystem shall also be capable of monitoring the load valuescontinuously during testing.NOTE 2Tests at multiple frequencies can be done. The frequencies ofFIG. 1 Sample with Loading Strip PartsD7369 1120.33 and 0.5 Hz are suggested.6.4.
34、2 Deformation MeasurementBoth horizontal and ver-tical deformation shall be measured on the surface of thespecimen by mounting LVDTs between gauge points along thehorizontal and vertical diameters. The gauge length can be ofthree sizes in relation to the diameter of the specimen:14 of thediameter or
35、 25.4 mm for a 101.6 mm-diameter of the specimen(1 in. for a 4 in.) or 38.1 mm for a 152.4 mm-diameter of thespecimen (1.5 in. for a 6 in.),12 of the diameter or 50.8 mm fora 101.6 mm diameter of the specimen (2 in. for a 4 in.) or 76.2mm for a 152.4 mm diameter of the specimen (3 in. for a 6 in.)an
36、d one diameter or 101.6 for a 101.6 mm diameter of thespecimen (4 in. for a 4 in.) or 152.4 mm for a 152.4 mmdiameter of the specimen (6 in. for a 6 in.). It is required tohave the two LVDTs, on each face of the specimen, onehorizontal and one vertical resulting in a total of four LVDTsfor deformati
37、on measurement.NOTE 3The results obtained with gauge length of14 of the diameterof the specimen have the best precision.6.4.3 Load MeasurementThe repetitive loads shall bemeasured with an electronic load cell with a capacity adequatefor the maximum required loading and a sensitivity of 0.5 % ofthe i
38、ntended peak load. During period of resilient modulustesting, the load cell shall be monitored and checked, once amonth, with a calibrated proving ring to ensure that the loadcell is operating properly. Additionally, the load cell shall bechecked at any time that the QC/QA testing with in-housesynth
39、etic specimen (see 9.1) indicates a change in the systemresponse or when there is a suspicion of a load cell problem.6.5 Loading StripSteel loading strips, with concavesample contact surfaces, machined to the radius of curvature ofa 101.60 6 0.10 mm diameter specimen (4.000 6 0.004 in) or152.40 6 0.
40、15 mm diameter specimen (6.000 6 0.006 in), arerequired to apply load to the test specimens. The contact areasof the loading strips shall be 12.7 mm (12 in.) and 19 mm (34in.) wide respectively for the 4 in specimen and 6 in specimen.The outer edges of the curved surface shall be filed lightly torem
41、ove sharp edges that might cut the specimen during testing.Thin lines should be drawn along the length of the strip at itscenter, to help alignment. Also, appropriate marking should bemade so as to center the specimen within the length of thestrips. This could be either done by matching the center o
42、fspecimen with a mark at the center of the strip or bypositioning the specimen between two marks at the ends of thespecimen thickness, or both.6.6 Marking and Alignment Devices:6.6.1 The LVDT alignment device should align the horizon-tal and vertical LVDTs simultaneously on the top and bottomfaces o
43、f the specimen for gluing. If such a device is not usedthen a marking device shall be used to mark mutually perpen-dicular axes on the top and bottom faces of the specimenthrough the center. The axes shall be simultaneously marked onthe top and bottom faces of the specimen to ensure that the axeson
44、the front and the back lie in a single plane.6.6.2 An alignment device shall be used to position andplace horizontal and vertical supports for gages or LVDTsalong the horizontal and vertical diameter of the specimen andhold them there until the glue that holds the supports cures. Itshall be easily r
45、emovable, without disturbing the LVDT (oncethe glue cures), and shall not be destructively mounted on thespecimen. The device shall be capable of mounting the LVDTat a gauge length of one-quarter and one half of the diameter ofthe specimen. The LVDT shall be as close as possible to (butnot touching)
46、 the surface of the specimen so as to minimize thebulging effect. To ensure uniform test results, a spacing of 5.08mm (0.2 in.) is recommended. The axis of the LVDT shall notbe at a distance greater than 6.35 mm (0.25 in.) from thesurface of the specimen. Fig. 2 shows an example of alignmentdevice.7
47、. Specimens7.1 Specimen SizeResilient modulus testing shall be con-ducted on 101.6 6 3.8 mm (4 in.) or 152.4 6 9 mm (6 in.)diameter specimens that are 38.1 mm (1.5 in.) to 63.5 mm (2.5in.) in thickness. The test specimen can be obtained from fieldcoring or from a Marshall-compacted specimen or from
48、agyratory-compacted specimen. Depending on the height of thegyratory-compacted specimen and the thickness of the testspecimen, two or three specimens can be sawed from acompacted specimen.7.2 Core Specimens:7.2.1 Cores for test specimen preparation, which may con-tain one or more testable layers, mu
49、st have smooth and uniformsurfaces and must meet specimen diametric and thicknessrequirements summarized in 7.1. Cores that are obviouslydeformed or have any visible cracks must be rejected. Irregulartop and bottom surfaces shall be trued as necessary, andindividual layer specimens shall be obtained by cutting with adiamond saw using water or air as coolant. Additional speci-mens for each layer must be collected in the field in order toperform the pretest tensile strength.7.2.2 If a core specimen has more than one layer, the layersshall be separated
