comparison of alternative asphalt concrete rut characterization

BERTHELOT, CROCKFORD & LYTTON 18Figure 5 Failed SHRP Shear Test Sample4.5 Rapid Triaxial CharacterizationTriaxial testing has been used by the road industry to characterize all types of road materials [26, 27].However, drawbacks to traditional triaxial test apparatus include: limited stress state and test temperaturetesting capabilities; sample preparation and instrumentation is time consuming and therefore, notconducive to production testing; limited feedback control capabilities; limited dynamic testingcapabilities; and direct measurement of Poisson’s ratio is difficult. To overcome these drawbacks, thisstudy employed a new prototype full feedback controlled rapid triaxial test apparatus shown in Figure 6 tocharacterize the Radisson SPS-9A asphalt concrete mixes.Dynamic frequency sweep testing for characterizing road materials and is standardized in ASTM D3497.The real and imaginary components of the complex modulus may be expressed as:E *= E' + iE"where: E* = complex stiffness modulus (Pa)E’ = real component of stiffness modulus (Pa)E” = imaginary component of stiffness modulus (Pa)