SUMMARY OF PAVEMENT PERFORMANCE TESTS USING THE ACCELERATED LOADING FACILITY, 1986-1990

FHWA has been conducting pavement performance tests using the Accelerated Loading Facility (ALF) for more than 5 years. Tests have been performed at the FHWA Pavement Testing Facility (PTF) during two reserach projects and at in-service sites in Montana and Wyoming. The first phase of pavement research at the PTF established operations and data collection procedures and assessed the rationality of performance data collected with the ALF. Data obtained during the PTF Phase 1 research showed that pavement performance under the ALF loading followed the general trends observed through monitoring of various test roads and in-service pavements. The in-service testing program demonstrated the mobility of the ALF, and experience with site preparation, traffic control, and site restoration was obtained. The rutting performance of an asphalt mixture specifically designed to resist rutting was evaluated in a Montana field test, which showed that the use of the antirutting mixture may delay the development of rutting, but that plastic flow, which has been identified as the major cause of severe rutting, was not eliminated. The PTF Phase 2 research, which compared the damage potential of conventional dual and side-based single tires, featured the comparative testing capabilities of the ALF. In this experiment, the control was the dual-tire loading and the treatment was the wide-based single-tire loading. Findings to date show the wide-based single tire to be significantly more damaging to flexible pavements than conventional dual tires.