Cooling characteristics of thermochromic powder modified sand fog seal on asphalt pavement in summer high-temperature environment

Abstract

Reversible optical response can occur in thermochromic materials with temperature changes, which has great potential in the field of pavement temperature regulation. The thermochromic sand fog seal (TP-SFS) was proposed in this study, which has the functions of pavement repair and temperature control. In this study, different types (red, blue, black) and contents (0 %, 2 %, 4 %, 6 %, and 8 %) of thermochromic powders (TP) were used to prepare TP-SFS. Secondly, the cooling characteristics of different TP-SFS was explored from the perspectives of temperature change rate, cooling temperature, and temperature gradient, based on the designed indoor and outdoor multi-cycle illumination test. Then, the prediction model of the outdoor cooling effect was proposed. In addition, the conservation and environmental benefits of different TP-SFS were calculated according to the empirical formula. It is found that after spraying TP-SFS, the heating rate of pavement decreases and the cooling rate increases. The cooling effect at 2 cm depth of the pavement sprayed with TP-SFS is the most significant, and the temperature gradient of the pavement is reduced. The cooling temperature of the pavement increases with the increase of TP content. In the outdoor environment, the more obvious cooling effect occurs as the process of pavement temperature increases and decreases. Additionally, the reliability of the designed indoor test is high, and the cooling effect of TP-SFS in outdoor environment can be well predicted according to the proposed model. The results of empirical formula calculation show that TP-SFS has a significant effect on delaying rutting development and alleviating urban heat island effect.