evaluation of performance grade of modified bitumen with waste crumb rubber using SHRP and SHRP plus tests

The direct impact of bitumen properties on the performance of asphalt mixtures has made bitumen behavior modification one of the key issues for researchers. Studies in this area have shown that waste Crumb Rubber have positive and acceptable effects on classical behavior of bitumen, but the rheological behavior of bitumen has been less studied. In this study, 8, 12 and 16 percent of Waste Crumb Rubber (#80 sieve size) by the weight of bitumen were used and then SHRP tests including Rotational Viscometer (RV), Dynamic Shear Rheometer (DSR), Bending Beam Rheometer (BBR), Rolling Thin-Film Oven (RTFO) and Pressure Aging Vessel (PAV) and SHRP Plus test including Multiple Stress Creep Recovery (MSCR) were performed on the samples .finally the Performance Grade (PG) of bitumens was evaluated by standard method and also by the results of MSCR test. The results showed that with increasing CR percentage, viscosity and high temperature PG increased so that the sample containing 16 percent CR had the highest temperature grade. also aging after RTFO had no effect on high temperature of PG.Increasing the CR had a positive effect on Jnr and increased the elastic behavior and consequently the bitumen's rutting resistance, especially the specimen containing 16 percent CR achieved the H traffic level which included heavy traffic load (10 to 30 ESALs) or slow moving. It also improved the low-temperature performance of bitumen for samples containing 8 and 16 percent of CR. review of the PG map of Iran showed that bitumen containing waste Crumb rubber is usable in most parts of the country