Investigation of the performance properties of asphalt binders and mixtures modified by Crumb Rubber and Gilsonite

The mechanical performance properties of asphalt binders and mixtures can be enhanced by utilizing several modifiers, including Crumb Rubber (CR) and gilsonite. The current study evaluated the effects of CR and gilsonite additive on the rheological behavior of gilsonite and CR/gilsonite composite modified binders and Stone Matrix Asphalt (SMA) mixtures. In this research, to modify original binder, gilsonite (0%, 10%, 20%, 30% and 40% by weight of binder), and CR (5%, 10%, 15%, and 20% by weight of binder) were used. The modified binders were subjected to rotational viscosity (RV), dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR), and linear amplitude sweep (LAS) tests. Also, the gilsonite and CR/gilsonite modified mixtures were subjected to four-point beam fatigue (FPBF), resilient modulus (Mr), indirect tensile strength (ITS), dynamic creep, and wheel track tests. The results revealed that the utilization of gilsonite reduced the low temperature cracking resistance of binders while adding CR to gilsonite modified binders, the low-temperature cracking of modified binders enhances. According to the results, utilization of gilsonite causes a decrease in the resistance of binders against fatigue cracking, while adding CR to gilsonite modified binders, the fatigue life of binders increases. Results revealed that both gilsonite and CR enhance the elasticity and recovery properties of binders, and consequently, the strength of binders versus permanent deformation improves. Mixture test results revealed that using gilsonite and CR increases the Mr, permanent deformation resistance, tensile strength, fracture energy, and intermediate temperature performance of specimens. It can be concluded from the results that CR has a positive impact on enhancing the gilsonite modified binders and mixtures performance.