1、Designation: D 7552 09Standard Test Method forDetermining the Complex Shear Modulus (G*) OfBituminous Mixtures Using Dynamic Shear Rheometer1This standard is issued under the fixed designation D 7552; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、case of revision, 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 the determination of the com-plex shear modulus of bituminous mi
3、xtures using torsionrectangular geometry on a dynamic shear rheometer (DSR). Itis applicable to bituminous mixtures having complex shearmodulus values greater than 1 3 104Pa when tested over arange of temperatures from 10C to 76C at frequencies of 0.01to 25 Hz and strains of 0.001 % to 0.1 %. The de
4、termination ofcomplex shear modulus is typically determined at 20C to70C at 0.01% strain at 10 discrete frequency values covering0.01 to 10 Hz. From these data, temperature or frequencymaster curves can be generated as required. This test method isintended for determining the complex shear modulus o
5、f bitu-minous mixtures as required for specification testing or qualitycontrol of bituminous mixture production.1.2 This test method is appropriate for laboratory preparedand compacted mixtures, field produced and laboratory com-pacted mixtures or field cores, regardless of binder type orgrade and r
6、egardless of whether RAP is used in the mixture.Due to the geometry of the specimens being tested this testmethod is not applicable to open-graded or SMA mixtures. Ithas been found to be appropriate for dense-graded mixtures,whether coarse- or fine-graded, with 19 mm or smaller nominalmaximum aggreg
7、ate size.1.3 The between-laboratory reproducibility of this testmethod is being determined and will be available on or beforeJune 2012. Therefore, this test method should not be used foracceptance or rejection of materials for purchasing purposes.1.4 The values stated in SI units are to be regarded
8、asstandard. No other units of measurement are included in thisstandard.1.5 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 safety and health practices and determine th
9、e applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction MaterialsD 140 Practice for Sampling Bituminous MaterialsD 2041 Test Method for Theoretical Maximum SpecificG
10、ravity and Density of Bituminous Paving MixturesD 2726 Test Method for Bulk Specific Gravity and Densityof Non-Absorptive Compacted Bituminous MixturesD 3203 Test Method for Percent Air Voids in CompactedDense and Open Bituminous Paving MixturesD 3666 Specification for Minimum Requirements forAgen-c
11、ies Testing and Inspecting Road and Paving MaterialsD 6752 Test Method for Bulk Specific Gravity and Densityof Compacted Bituminous Mixtures Using AutomaticVacuum Sealing MethodD 6857 Test Method for Maximum Specific Gravity andDensity of Bituminous Paving Mixtures Using AutomaticVacuum Sealing Meth
12、odD 6925 Test Method for Preparation and Determination ofthe Relative Density of Hot Mix Asphalt (HMA) Speci-mens by Means of the Superpave Gyratory CompactorD 6926 Practice for Preparation of Bituminous SpecimensUsing Marshall ApparatusD 7175 Test Method for Determining the Rheological Prop-erties
13、of Asphalt Binder Using a Dynamic Shear Rheom-eterD 7312 Test Method for Determining the Permanent ShearStrain and Complex Shear Modulus of Asphalt MixturesUsing the Superpave Shear Tester (SST)E77 Test Method for Inspection and Verification of Ther-mometersE 563 Practice for Preparation and Use of
14、an Ice-Point Bathas a Reference TemperatureE 644 Test Methods for Testing Industrial Resistance Ther-mometers1This 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 Tests.Current e
15、dition approved July 1, 2009. Published August 2009.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyrigh
16、t ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2.2 Other Standards:DIN Standard 43760 Standard for Calibration of PlatinumResistance Thermometers33. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 asphalt binder, nan asph
17、alt-based cement that isproduced from petroleum residue either with or without theaddition of non-particulate modifiers.3.1.2 calibration, na process that establishes the relation-ship (traceability) between the results of a measurementinstrument, measurement system, or material measure and thecorre
18、sponding values assigned to a reference standard. Cali-bration is typically performed by the manufacturer or anexternal commercial calibration service.3.1.3 complex shear modulus (G*), na complex numberthat is defined by the ratio of shear stress to shear strain.3.1.4 dummy test specimen, na rectang
19、ular prismatic orcylindrical specimen of bituminous mix prepared as discussedin Section 9.2, into which a small hole is drilled and into whicha PRT wire is inserted. The dummy specimen is then mountedin the torsion fixture of the DSR for the purpose of determiningthe temperature in the bituminous mi
20、xture. In addition thedummy specimen can be used to ascertain the amount of timeneeded to bring a test specimen to the appropriate testtemperature.3.1.4.1 DiscussionThe dummy test specimen is not usedto measure the modulus characteristics of the bituminousmixture but is used to determine temperature
21、 corrections andequilibrium times.3.1.5 loading cycle, nrefers to the application of sinusoi-dal stress or strain loading for a specified duration.3.1.6 shear stress, nthe force per unit area that producesthe flow.3.1.7 portable thermometer, nrefers to an electronic de-vice that is separate from the
22、 dynamic shear rheometer and thatconsists of a detector (probe containing a thermocouple orresistive element), associated electronic circuitry, and readoutsystem.3.1.8 reference thermometer, nrefers to a NIST-traceableliquid-in-glass or electronic thermometer that is used as alaboratory standard.3.1
23、.9 temperature correction, ndifference in temperaturebetween the temperature indicated by the DSR and the testspecimen as measured by the portable thermometer insertedbetween the test plates.3.1.10 thermal equilibrium, ncondition where the tem-perature of the test specimen mounted between the test p
24、latesis constant with time.3.1.11 verification, na process that establishes whetherthe results of a previously calibrated measurement instrument,measurement system, or material measure are stable. Usuallyperformed internally within the operating laboratory.4. Summary of Test Method4.1 This standard
25、contains the procedure used to measurethe complex shear modulus of a bituminous mixture using aDSR in oscillatory mode and using torsional rectangulargeometry. The DSR must be temperature-controlled using aforced air system.4.2 The standard is suitable for use when the complex shearmodulus is greate
26、r than 1 3 104Pa at the test temperature. Thecomplex shear modulus is typically determined at 20C to70C, although other test temperatures may be used.4.3 Test specimens, nominally 49 6 2 mm in length, 12 62 mm in width and 9 6 1.5 mm in thickness may be cut fromgyratory or Marshall laboratory specim
27、ens or from field cores(see Figs. 1-3). Specimens can be obtained from bituminousmixture samples compacted using other devices as long as it ispossible to determine the air voids of the mixture samples. Thetest specimens are mounted with the 49 6 2 mm lengthforming a vertical dimension in the DSR.4.
28、4 During testing, one of the fixtures4is rotated withrespect to the other at a pre-selected % strain and a range offrequencies at the selected temperatures. The test shall beconducted at 0.01 % strain unless otherwise stated. The %strain stipulated in this test method has been found to produceaccept
29、able results for the bituminous materials investigated todate.NOTE 1Different strain values, within the capabilities of individualequipment, may be selected for testing materials beyond the scope ofthose tested to date. Regardless of % strain or test temperatures chosen ortest materials investigated
30、, the basic testing process described herein willnot change.4.5 The test specimen is maintained at the test temperature60.1C by enclosing the upper and lower fixtures in athermally controlled environmental test chamber.5. Significance and Use5.1 The complex shear modulus of bituminous mixtures is af
31、undamental property of the material. Test results at criticaltemperatures (Tcritical) are used for specifications for somemixes. Mixtures with stiffer binders, aged mixtures, mixtureswith higher amounts of fines (material finer than 75), andmixtures with lower voids all tend to have higher complexsh
32、ear modulus values than mixtures with less stiff binders,unaged mixes, mixtures with low levels of fines and higher airvoids. In general, mixtures with higher complex shear modulusvalues at a given service temperature will exhibit lowerpermanent deformation values than similar mixtures tested atthe
33、same temperature that have lower complex shear modulusvalues.NOTE 2The 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 St
34、andard Practice D 3666 are generallyconsidered capable of competent and objective testing/sampling/3Available from Beuth Verlag GmbH (DIN- DIN Deutsches Institut furNormung e.V.), Burggrafenstrasse 6, 10787, Berlin, Germany, http:/www.en.din.de.4Depending upon whether a stress or strain controlled r
35、heometer is being used,either the upper or lower fixture will be the one which is rotated. This test methodis applicable to both stress and strain controlled rheometers. When a stresscontrolled rheometer is used, the test is performed in strain controlled mode.D7552092FIG. 1 Schematic of Preparing T
36、orsion Rectangular SpecimensFIG. 2 Sample Preparation to Obtain 50-mm Wide by 12-mm Thick Rectangular SpecimenD7552093inspection/etc. Users of this standard are cautioned that compliance withD 3666 alone does not completely assure reliable results. Reliable resultsdepend on many factors; following t
37、he suggestions of D 3666 or somesimilar acceptable guideline provides a means of evaluating and control-ling some of those factors.6. Interferences6.1 Due to the nature of test geometry this test cannot beused to determine the complex shear modulus of rectangularspecimens obtained from SMA (Stone Ma
38、stic or MatrixAsphalt) or OGFC (Open Graded Friction Course) mixtures.Without confining pressure these specimens fall apart whenbrought to test temperature. At this point in time there is nosuitable method for imparting confining pressure on the testspecimens.6.1.1 The calculation of the complex she
39、ar modulus fromthe data obtained from the DSR is highly dependent upon anaccurate measurement of the dimensions of the test specimen.In the procedure, the length of the test specimen is the gapdistance between the mounting fixtures after the zero gapmeasurement of the torsion fixture has been made.
40、Once thetest specimen is mounted in the fixture, the length of specimenbetween the two mounting points is the length of the specimen.The width and thickness of the specimen is determined prior tomounting the specimen in the DSR using a digital caliper andis reported to the nearest 0.01 mm. These val
41、ues are enteredinto the software of the instrument where the test specimendimensions are requested. Due to the potential for variability inthe width and thickness due to the sample preparation proce-dure, the width and thickness is determined in the centralportion of the test specimen.7. Apparatus7.
42、1 The apparatus for performing the test as described inthis method shall be the equipment described in Test MethodD 7175 under the section heading of Apparatus except asamended below.7.2 Test FixturesTwo fixtures capable of securing therectangular test specimens with the long dimension of the testar
43、ticle in a vertical plane are required.7.3 A torque wrench capable of applying a torque load of0.25 Nm (250 mNm) 6 0.05 Nm of torque to tighten the testspecimen in the mounting fixture without crushing.7.4 Environmental ChamberA chamber for controllingthe temperature of the test specimens. The mediu
44、m used tocontrol the chamber shall be compressed laboratory air orcommercially bottled air. Chilled, compressed laboratory air orliquid nitrogen (LN2) is required if testing temperatures belowapproximately 30C is to be conducted. When laboratory air isused in a forced air environmental chamber, a su
45、itable dryermust be included to prevent condensation of moisture on thetest specimen. The environmental chamber and the temperaturecontroller shall control the temperature of the test specimenmounted between the grips, including any thermal gradientswithin the test specimen, at the test temperature
46、6 0.1C. Dueto the geometry and type of material being tested, water bathsand Peltier fixtures cannot be used to control the test tempera-ture of the specimens. Some companies manufacture a Peltierheated submersion cell, which uses water or some other liquidmedium to condition the test specimen. Test
47、ing the mixturewhile submerged could introduce errors in the results due toweakening of the mix due to moisture interaction.FIG. 3 Sample Preparation to Obtain 50-mm Wide by 12-mm Wide by 10-mm Thick Specimen.D75520947.5 Temperature ControllerA temperature controller ca-pable of maintaining the temp
48、erature of the test specimen at thetest temperature 60.1C for test temperatures stipulated.7.6 Internal DSR ThermometerA platinum resistancethermometer (PRT) mounted within the environmental cham-ber as an integral part of the DSR and in close proximity to thebottom mounting fixture with a minimum r
49、ange of 30C to82C, and with a resolution of 0.1C. Normally this range willbe sufficient unless there is a need to determine the complexshear modulus of the mixture at temperatures below ambient. Ifthere is a need to control test temperatures below ambient thenmechanical cooling or liquid nitrogen will be needed. Thisthermometer shall be used to control the temperature of the testspecimen and shall provide a continuous readout of tempera-ture during the mounting, conditioning, and testing of thespecimen.NOTE 3Platinum resistance thermometers (PRTs
