Laboratorial Investigation on Optical and Thermal Properties of Thermochromic Pavement Coatings for Dynamic Thermoregulation and Urban Heat Island Mitigation

Abstract

• Optical and thermal properties of thermochromic materials are compared with the traditional reflective materials. • Two kinds of thermochromic coatings are developed considering temperature adjusting and visual effect. • Thermochromic coatings can bring 10.57°C cooling effect and icing delay benefit of road. • The thermochromic pavement is more effective than reflective pavement for urban microclimate improvement. With the rapid process of urbanization, asphalt pavement has become the main pavement type of urban roads, which absorbs solar radiation severely in summer and aggravates urban heat island effect (UHI). Reflective coating is regarded as one of the most effective ways to solve above problems in summer but may bring certain negative effects in winter. In this paper, two kinds of thermochromic (TCM) coatings were developed, which could achieve dynamic thermoregulation. The results showed that comprehensively considering both reflectance characteristics and visual effect (anti-glare), TCM materials in red and black were more suitable to be used in thermoregulation coatings for pavement, and the optimal TiO 2 contents in red/black TCM coating was 2wt%/5wt%. The cooling effect of TCM coating was 2-5 ℃ higher than that of cool coating with the same color, and it could delay the time for road surface temperature to drop to 0°C to some extent. Besides, CFD simulation results showed that average air temperature at 1.5m of thermochromic pavement was lower than traditional reflective pavement. This study will provide references and insights for preparation of thermochromic coating to mitigate UHI and minimize the negative impact on the light-thermal environment of pavement at the same time.