COMPARATIVE PERFORMANCE OF RUBBER MODIFIED HOT MIX ASPHALT UNDER ALF LOADING

Experiment 2 at the Louisiana Accelerated Loading Facility (ALF) site involved determining the engineering benefits of using powdered rubber modifier (PRM) in hot mix asphalt mixes. Three full scale test sections were constructed and subjected to increasing loads from the ALF. Lane 2-1 included PRM in the wearing course, lane 2-2 included PRM in the base course, and lane 2-3 was the control section. Distress and deflection measurements were performed every 25,000 applications of the ALF. Laboratory material characterizations of test lane materials were used in ABAQUS and FLEXPASS modeling studies to predict the behavior and performance of the test lanes. Comparisons of observed and predicted rutting were developed and discussed. Deflection measurements were used to develop a-values for the powdered rubber modified layers for use in pavement design. The recommended a-value for the PRM wearing course was 0.25; it was 0.45 for the PRM base.