ASTM_D_6648_-_08.pdf

Designation:D664808Standard Test Method forDetermining the Flexural Creep Stiffness of Asphalt BinderUsing the Bending Beam Rheometer(BBR)1This standard is issued under the fixed designation D6648;the number immediately following the designation indicates the year oforiginal adoption or,in the 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.Scope21.1 This test method covers the determination of theflexural-creep stiffness or compliance and m-value of asphaltbinders by means of a bending beam rheometer.It is applicableto material having flexural-creep stiffness values in the range of20 MPa to 1 GPa(creep compliance values in the range of 50nPa1to 1 nPa1)and can be used with unaged material or withmaterials aged using aging procedures such as Test MethodD2872 or Practice D6521.The test apparatus may be operatedwithin the temperature range from 36C to 0C.1.2 Test results are not valid for test specimens that deflectmore than 4 mm or less than 0.08 mm when tested inaccordance with this test method.1.3 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 the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:3C802 Practice for Conducting an Interlaboratory Test Pro-gram to Determine the Precision of Test Methods forConstruction MaterialsD140 Practice for Sampling Bituminous MaterialsD2872 Test Method for Effect of Heat and Air on a MovingFilm of Asphalt(Rolling Thin-Film Oven Test)D6521 Practice for Accelerated Aging of Asphalt BinderUsing a Pressurized Aging Vessel(PAV)D6373 Specification for Performance Graded AsphaltBinderE77 Test Method for Inspection and Verification of Ther-mometers2.2 DIN Standard:4437603.Terminology3.1 Definitions:3.1.1 asphalt binder,nan asphalt-based cement that isproduced from petroleum residue either with or without theaddition of modifiers.3.1.2 physical hardening,na time-dependent,reversiblestiffening of asphalt binder that typically occurs when thebinder is stored below room temperature.3.2 Definitions of Terms Specific to This Standard:3.2.1 contact load,nthe load,Pc,required to maintainpositive contact between the test specimen,supports,and theloading shaft;35 6 10 mN.3.2.2 flexural creep compliance,D(t),nthe ratio obtainedby dividing the maximum bending strain(see Eq X1.5)in abeam by the maximum bending stress(Eq X1.4).The flexuralcreep stiffness is the inverse of the flexural creep compliance.3.2.3 flexural creep stiffness,Se(t),nthe creep stiffnessobtained by fitting a second order polynomial to the logarithmof the measured stiffness at 8.0,15.0,30.0 60.0,120.0,and240.0 s and the logarithm of time(see Eq 5,section 14.4).3.2.4 measured flexural creep stiffness,Sm(t),nthe ratio(see Eq 3,section 14.2)obtained by dividing the measuredmaximum bending stress(see X1.4)by the measured maxi-mum bending strain(see Eq X1.5).Flexural creep stiffness hasbeen used historically in asphalt technology while creepcompliance is commonly used in studies of viscoelasticity.3.2.5 m-value,nthe absolute value of the slope of thelogarithm of the stiffness curve versus the logarithm of time(see Eq 6,section 14.5).3.2.6 test load,nthe load,Pt,of 240-s duration used todetermine the stiffness of the asphalt binder being tested;9806 50 mN.1This test method is under the jurisdiction of ASTM Committee D04 on Roadand Paving Materials and is the direct responsibility of Subcommittee D04.44 onRheological Tests.Current edition approved Jan.15,2008.Published February 2008.Originallyapproved in 2001.Last previous edition approved in 2001 as D6648 01.DOI:10.1520/D6648-08.2This standard is based on SHRP Product 1002.3For 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.4Deutsches Institut fuer Normung(German Standards Institute),Beuth VerlagGmbH,Burggrafenstrasse 6,1000 Berlin 30,Germany.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.2.7 zero load cell readingthe load indicated by the dataacquisition system when the shaft is free floating in the bathand at the position that occurs when first making contact witha test specimen.4.Summary of Test Method4.1 The bending beam rheometer is used to measure themid-point deflection of a simply supported prismatic beam ofasphalt binder subjected to a constant load applied to itsmid-point.The device operates only in the loading mode;recovery measurements cannot be obtained with the bendingbeam rheometer.4.2 A prismatic test specimen is placed in the controlledtemperature fluid bath a