Effect of crumb tire rubber, microcrystalline synthetic wax, and nano silica on asphalt rheology

This study aims at exploring the influence of different modifiers on the physical and rheological properties of asphalt cements. Crumb Tire Rubber (CTR), Microcrystalline Synthetic Wax (MSW), and Nano Silica (NS) modifiers were used to modify asphalt cement of 60/70 penetration grade. Several percentages of CTR (9, 12, and 16%), MSW (2, 3.5, and 5%), and NS (3, 5, and 7%) by weight of the asphalt cement were tested. The penetration, softening point, flash and fire points, viscosity, dynamic shear rheometer (DSR), and bending beam rheometer (BBR) were carried out in this study. Experimental results showed an improvement in the high-temperature performance of asphalt cement by adding CTR and NS modifiers while adversely affecting properties at low temperatures. Also, the results did not show any enhancement in the high or low-temperature performance by adding MSW to the asphalt cement. The optimum contents of CTR and NS modifiers were found to be 12% and 5% by weight of the asphalt cement, respectively.