THE PERFORMANCE OF OVERLAY TREATMENTS AND MODIFIED BINDERS UNDER ACCELERATED LOADING: THE CALLINGTON ALF TRIAL

The Department of Road Transport in conjunction with the Australian Road Research Board has conducted a series of full scale pavement tests using the ARRB Accelerated Loading facility on the South East Highway near Adelaide. The aim of the trial was to test the relative performance of alternative forms of asphalt rehabilitation. An existing section of distressed pavement was repaired using a variety of thin overlay treatments and various thicknesses of asphalt reinstatement. A total of 17 loading experiments were conducted. The performance of the test sections was continually monitored by surface deflection bowls, transverse profile measurements and crack mapping. Strains were recorded in some asphalt layers and asphalt temperatures were continually logged at different depths. The test results and conditions are presented in a summarised format. Preliminary analysis has provided a ranking of deformation resistance of all asphalt materials used with some modified binders displaying significant advantages over conventional C 1 70 bitumen. Comparative overlay experiments have clearly demonstrated a significant extension in pavement life through use of a modified asphalt in the overlay.