ASTM_D_3497_-_79_2003.pdf

Designation:D 3497 79(Reapproved 2003)Standard Test Method forDynamic Modulus of Asphalt Mixtures1This standard is issued under the fixed designation D 3497;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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers procedures for preparing andtesting asphalt mixtures to determine dynamic modulus values.The procedure described covers a range of both temperatureand loading frequency.The minimum recommended test seriesconsists of testing at 41,77,and 104F(5,25,and 40C)atloading frequencies of 1,4,and 16 Hz for each temperature.1.2 This method is applicable to asphalt paving mixturessimilar to mixes 3A,4A,5A,6A,and 7A,as defined bySpecification D 3515.1.3 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:2C 617 Practice for Capping Cylindrical Concrete Speci-mensD 3496 Method for Preparation of Bituminous MixtureSpecimens for Dynamic Modulus TestingD 3515 Specification for Hot-Mixed,Hot-Laid BituminousPaving Mixtures3.Terminology3.1 Definitions:3.1.1 dynamic modulusthe absolute value of the complexmodulus that defines the elastic properties of a linear viscoelas-tic material subjected to a sinusoidal loading,?E*?3.1.2 complex modulusa complex number that defines therelationship between stress and strain for a linear viscoelasticmaterial,E*.3.1.3 linear materiala material whose stress to strain ratiois independent of the loading stress applied.4.Summary of Test Method4.1 A sinusoidal(haversine)axial compression stress isapplied to a specimen of asphalt concrete at a given tempera-ture and loading frequency.The resulting recoverable axialstrain response of the specimen is measured and used tocalculate dynamic modulus.5.Significance and Use5.1 The values of dynamic modulus can be used for bothasphalt paving mixture design and asphalt pavement thicknessdesign.6.Apparatus6.1 Testing MachineAn electro-hydraulic testing machinewith a function generator capable of producing a haversinewave form has proven to be most suitable for use in dynamicmodulus testing.The testing machine should have the capabil-ity of applying the loads over a range of frequencies from 0.1to 20 Hz and stress levels up to 100 psi(690 kPa).6.2 Temperature-Control SystemThe temperature-controlsystem should be capable of a temperature range from 32 to120 6 1F(0 to 50 6 0.5C).The temperature chamber shouldbe large enough to hold six specimens.6.3 Measurement SystemThe measurement system con-sists of a two-channel recorder,stress-and strain-measuringdevices,a suitable signal amplification,and excitation equip-ment.The measurement system should have the capability fordetermining loading up to 3000 lbf(13.3 kN)from a recordingwith a minimum sensitivity of 2%of the test load permillimetre of chart paper.This system should also be capablefor use in determining strains over a range of full-scalerecorder outputs from 300 to 5000 micro units of strain.At thehighest sensitivity setting,the system should be able to display4 micro strain units or less per millimetre on the recorded chart.6.3.1 RecorderThe recorder amplitude should be inde-pendent of frequency for tests conducted up to 20 Hz.6.3.2 Strain MeasurementThe values of axial strain aremeasured by bonding two wire strain gages3at mid-heightopposite each other on the specimens.The gages are wired ina Wheatstone Bridge circuit with two active gages on the testspecimen and two temperature-compensating gages on an1This test method is under the jurisdiction of ASTM Committee D04 on RoadPaving Materials and is the direct responsibility of Subcommittee D04.26 onFundamental/Mechanistic Tests.Current edition approved Oct.26,1979.Published December 1979.Originallyapproved in 1976.Last previous edition approved in 1995 as D 3497 79(1995).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.3The Baldwin-Lima-Hamilton SR-4 Type A-1S 13 strain gage has been foundsatisfactory for this purpose.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.unstressed specimen exposed to the same environment as thetest specimen.The temperature-compensating gages should beat the same position on the specimen as the active gages.Thesensitivity and type of measurement device should be selectedto provide the strain readout required in 6.3.6.3.3 Load MeasurementsLoads are