Thermal performances of asphalt mixtures using recycled tyre rubber as mineral filler

Abstract

As the global temperature rises in the summer, researchers are paying more attention to cool pavements. Rubberised asphalt, made by mixing shredded crumb rubber into asphalt and used on road and highway pavements, is being regarded as one of the potential cool pavements. This research aims to investigate the thermal performances of asphalt binders and mixtures containing recycled tyre rubber (RTR) powder. The experimental design for this research included asphalt binders and mixtures with different contents of RTR powder. The thermal conductivity coefficients and heat capacities of asphalt binders and mixtures were measured besides vertical temperature distributions of mixtures; meanwhile, water sensitivity and high-temperature properties of mixtures were also investigated in this study. The experimental results show that the addition of RTR powder is helpful in reducing the thermal conductivity coefficient of asphalt binders and mixtures, while it has an opposite effect on volumetric heat capacity for asphalt binders and mixtures. With an increasing content of RTR powder, the heat capacity of the binder is decreased but that of the mixture is increased. And the surface temperature of an asphalt mixture containing RTR powder as mineral filler is higher than that of a control sample in solar heating simulation tests, while the inner temperature is reverse. The use of RTR as mineral filler in an asphalt mixture is helpful in improving the thermal stability of the asphalt mixture, but it slightly reduced the moisture resistance in this study.