VALIDATION EXPERIMENTS FOR PERMANENT DEFORMATION TESTING OF BITUMINOUS MIXTURES (WITH DISCUSSION)

Results from repeated load uniaxial compression and small-scale wheel tracking tests both correctly ranked four different asphalt concrete mixtures with respect to rutting performance in pilot-scale experiments. The mixtures involved a "good" and "poor" aggregate and a standard and an SBR modified binder. It was found to be desirable for the binder stiffness in the compression tests to match that in the pavement because of the significant influence which the binder has on permanent deformation resistance of dense mixtures. Using an internal partial vacuum to apply a confining stress in repeated load compression tests produced appropriate conditions for testing materials which rely strongly on aggregate characteristics to mobilize permanent deformation resistance.