Laboratory investigation of the effect of crumb rubber on the characteristics and rheological behaviour of asphalt binder

Effects of crumb rubber (CR) addition on performance characteristics of asphalt binder and evaluating the optimised level of additive are studied with both conventional and strategic highway research program (SHRP) tests. Five different amounts of CR, that is, 4%, 8%, 12%, 16% and 20%, were added to 60/70 pure asphalt binder and, then conventional and SHRP test methods were implemented with rotational viscosity and the dynamic shear rheometer, in three cases, that is, the main asphalt binder, aged with a rolling thin film oven and a pressure ageing vessel. Results show that modification of pure asphalt binder with CR, in mass per cents greater than 8 with respect to initial pure asphalt binder, will result in one or two degrees improvement in the performance of the asphalt binder, and will also increase the amount of G*/Sin δ (rutting criterion) at several temperatures for the before and after ageing in rolling thin film oven test, and reduction in the grade fatigue crack mechanism (G* × Sin δ) in middle service temperatures of pavement. Modification of pure asphalt binder with CR will increase its viscosity, and with an increase in the amount of CR, the rotational viscosity will also increase.