Moisture damage potential of Reclaimed Asphalt Pavement (RAP) in bituminous mixes by ultrasonic pulse velocity

Abstract

Ultrasonic pulse velocity (UPV) test has been used for decades to evaluate the performance of cement concrete. But in recent ages, the use of the UPV test for bituminous concrete (BC) has been increased worldwide. Evaluation of the moisture damage effect of Reclaimed Asphalt Pavement (RAP) enriched BC in terms of dynamic modulus, obtained by UPV test, is a holistic approach of the present study. Several percentages of RAP such as 0%, 10%, 20%, 30%, 40%, 50%, 60%, 75% and 100% were used to prepare bituminous concrete mix in view to determine the percentage of RAP aggregate which produces the highest moisture resistive bituminous concrete mix. Marshall mix design method was applied to achieve the Marshall volumetric parameters and different optimum bitumen contents (OBCs). In this present study, the UPV test on RAP modified BC mix was carried out to determine the dynamic modulus at pre-estimated OBCs at prolonged soaking period (i.e., 0, 1, 4, and 7th days), by maintaining the temperature of the water bath at 60 °C. The results of the investigation explored that 50% RAP modified bituminous mix performed better than the other studied mixes in terms of dynamic modulus from the UPV test with 0.03% less bitumen content than the control mix. So, the 50% RAP material in the BC may be considered to produce the most durable and moisture resistive bituminous mix and it serves the longer span life of the flexible pavement.