Effects of Crumb Rubber as Coarse Aggregate Replacement on the Fatigue Property of Warm Mix Asphalt

Abstract

One of the innovative techniques for increasing the fatigue resistance of flexible asphalt pavement is to partially substitute aggregate in asphalt concrete mixtures with crumb rubber from discarded tires. However, it is still unclear how effective warm mix asphalt is and what proportion of CRM provides the highest fatigue resistance. This study's objective is to assess how much crumb rubber in warm mix asphalt mixtures affects fatigue. A warm mix binder was created by blending a Pen-grade 60/70 bitumen with Sasobit at a weighted percentage of 2.5%. Using a dry process of modification, crumb rubber that could pass through a 12.5 mm screen was added to WMA mixtures at a rate of 0., 10., 15., 20., 25., and up to 50% of the weight of virgin bitumen. The specimens underwent an indirect tensile fatigue test (ITFT) on them at a temperature of 25°C. The mix design obtained by RSM resulted in the production of 30 samples. Three different levels of stress (500., 600., and 700 kPa) were used during the test. the resilience modulus test and the three-point flexural beam test. The findings demonstrated that when temperature and loading rate increase, the rubber asphalt mixture's strength falls and increases, respectively. According to the results of the RSM analysis, the optimal asphalt content for this study is 4.018% asphalt, 20% crumb rubber, 46% coarse aggregate, 10% fine aggregate, and 15% mineral filler.