Volume 40, Issue 5 (September 2012)
Effect of Phase-Change Materials on Thermal and Mechanical Properties of Asphalt Mixtures
The use of phase-change materials (PCMs) in asphalt mixture is expected to solve some problems related to asphalt-pavement temperature, such as rutting behaviors and urban heat island effect. This study mainly evaluated the thermal and mechanical properties of asphalt mixtures with and without various PCMs (PCM-L, PCM-Z) using laboratory performance tests. The experimental tests included thermal conductivity and diffusivity, volumetric heat capacity, indoor temperature changes versus time when heated or cooled, indirect tensile strength, high-temperature rutting, and low-temperature cracking. In addition, a hot disk thermal constants analyzer was used to measure the thermal constants of asphalt mixtures. The results showed that different PCMs had different effects on the thermal constants of asphalt mixtures. Compared with control sample, the sample with PCM-L showed a higher thermal conductivity, whereas the sample with PCM-Z had a lower thermal conductivity. Moreover, PCM-Z exhibited a more-significant phase-change adjusting-temperature effect on asphalt mixtures than PCM-L. However, the addition of PCM to asphalt mixtures resulted in a decreased indirect tensile strength and a weakened rutting resistance, but the effect of PCM-Z was smaller than that of PCM-L. In addition, the asphalt mixture with PCM-Z exhibited better cracking resistance than the mixture with PCM-L and control mixture. Therefore, it is recommended to use PCM-Z in asphalt mixtures to solve the problem of pavement at high temperatures.