Rutting and Resilient Modulus Behavior of Asphalt Concrete Modified with Crump Tire Rubber, Microcrystalline Synthetic Wax and Nano Silica

Abstract

This study explores the effect of three types of modifiers on the rutting and resilient modulus performance of asphalt concrete mixtures using the dynamic creep test. Modifiers have been added to the asphalt binder at optimum percentages that have been chosen based on a previous study by the authors. 108 Superpave asphalt mixture specimens have been prepared. In this study, the dynamic creep test has been conducted at different temperatures (25 °C, 40 °C and 55 °C) and at three loading frequencies (1, 4 and 8 Hz). Accumulated axial micro-strain, creep stiffness modulus, and resilient modulus values have been measured. The results have showed an enhancement in the rutting resistance at high frequencies when adding the modifiers. The Crump Tire Rubber modified mixtures have showed the best results at high temperatures, and the Nano Silica modified mixtures had the best outcomes at intermediate temperatures, while the Microcrystalline Synthetic Wax modified mixtures have achieved the best results at lower temperatures. Statistical and regression analyses have showed that changing temperature, frequency, and modifier type had a significant effect on the accumulated axial micro-strain, creep stiffness modulus, and resilient modulus values. Models have been generated with relatively high coefficients of determination (R2) and adjusted R2, indicating their ability in explaining much of the variability in the response variables.