Evaluation of degree of blending and its effect on performance of recycled hot-mix asphalt under different preheating conditions

Abstract

This research comprehensively explored the function of preheating temperature and quantified the contribution of degree of blending (DoB) to performance of recycled hot-mix asphalt (HMAs). Five groups were designed, including no blending group, full blending group, and three experimental groups at preheating temperatures of 60, 110, and 160 °C. It can be found that the preheating temperature played a positive impact on DoB and performance of recycled HMAs. As the preheating temperature increased by 50 °C, about 0.13%–0.2% of reclaimed asphalt binder can be additionally activated, and the tensile strength ratio, shear strength, and fracture energy of recycled HMAs can improve by around 6%–8%, 0.07–0.15 MPa, and 304.2–335.4 J·m2, respectively. Moreover, the results showed that the performance of recycled mixes designed at preheating temperature of 60 °C was close to that of no blending group, while the mixes designed at a preheating temperature of 160 °C can reach to those of full blending group.