Temperature Sensitivity of Mechanical Properties of Cement Asphalt Mortar with Nanoparticles

Cement asphalt mortar (CAM) in high-speed lines is subjected to varying environmental conditions, which lead to the deterioration of CAM. The nanoparticles of nano-SiO2 and nano-TiO2 are added to improve the performance of CAM, and the temperature sensitivity of CAM with nanoparticles is primarily studied in this paper. The flexural strength and compressive strength of CAM with and without nano-SiO2 and nano-TiO2 were measured and compared to study the effect of nanoparticles on the performance of CAM subjected to different temperatures. Temperature sensitivity factors of flexural and compressive strength based on Arrhenius model were proposed to evaluate the temperature dependence of CAM by nanoparticles. Furthermore, the microstructure of hardened CAM was studied using scan electronic microscope (SEM) to investigate the mechanism of temperature sensitivity of CAM with and without nanoparticles. The results indicated that the flexural and compressive strength of CAM with and without nanoparticles decreased with the increasing temperature; however, the decreasing rate of strength with temperature was different in CAM with and without nanoparticles. The reduction in the decreasing rate of strength was obtained by using nano-SiO2 rather than nano-TiO2 in CAM. Based on the SEM results, the free asphalt was seen to be greatly reduced in the CAM with nano-SiO2, suggesting a positive effect of nano-SiO2 on the mitigation of temperature sensitivity of CAM.