Effect of Crumb Rubber Modifier on the Fatigue Performance of Warm Mix Asphalt

Crumb rubber from waste tires is incorporated into asphalt mixtures as one of the successful strategies of improving the fatigue resistance of asphalt pavement. However, the degree of effectiveness and the percentage of CRM that gives the best fatigue resistance has not been firmly established. In this study, the effect of percentage crumb rubber on fatigue of rubberised warm mix asphalt mixtures was evaluated. A Pen-grade of 80/100 bitumen, crush granite aggregate with 9.5 mm NMAS, Sasobit at 2.5% by weight of the binder was blended with the bitumen to achieve a warm mix binder. Crumb rubber of size passing 0.150 mm sieve was incorporated into the WMA mixes at 0, 10 15 and 20% by weight of the virgin bitumen using wet process of modification. Indirect Tensile Fatigue Test (ITFT) was performed on the specimens at a temperature of 25 °C. The test was conducted at three levels of stresses (500, 600 and 700 kPa). The laboratory results findings indicate that the CRM significantly influence the fatigue life of the mixtures. Based on the fatigue predictive life model, the 20% CRM have the highest fatigue life compared to other CRM percentages considered in this study.