Improvement on rheological property of asphalt binder using synthesized micro-encapsulation phase change material

Abstract

Temperature is a governing parameter that affects the rheological property of asphalt binder. Upon cooling, bitumen becomes stiffer and prone to thermal cracking. To reduce the negative impact of temperature, utilizing the thermal energy storage of phase change material is a promising solution. This study provides an approach to synthesize micro-encapsulation phase change material (μPCM) and its application to enhance the binder’s rheological property and mitigate black ice. Two μPCMs were prepared with n-Tetradecane as a core, while Calcium carbonate (CaCO3) and Silicate (SiO2) as a shell. SEM test exhibited that μPCM had a spherical shape with a diameter ranging from 1 to 7 μm. Meanwhile, thermogravimetric analysis proved that the encapsulation method could protect and prevent leakage of n-Tetradecane under high temperature. The residual weight of CaCO3-μPCM was 95% and 84% at 160 °C and 350 °C, respectively. The differential scanning calorimeter results showed that the encapsulation ratio was approximately 52.9% (ΔH = 99.94 W/g). Moreover, different μPCM modified asphalt binders were examined to evaluate the rheological property. Results from rotational viscosity test at 135 °C pointed out that adding μPCM did not affect binder viscosity. DSR test showed that the incorporation of μPCM could reduce binder stiffness at low temperatures. The thermal effect of μPCM was analyzed by low-temperature sweep test. With simultaneous cooling, μPCM released latent heat, thus increasing the binder’s temperature by 1.5 °C. The low values of G*sinδ indicated the outperformance of μPCM-binder compared to conventional binder in terms of thermal cracking resistance.