Assessment of optical-thermal balance and environmental degradation of a thermochromic-coated asphalt mixture for urban heat mitigation

Thermochromic coatings offer a promising solution to reduce pavement heat absorption and mitigate urban heat island (UHI) effects. While surface spray techniques enhance thermochromic performance by creating a reflective top layer, environmental exposure can significantly diminish their durability. This study evaluates the cooling performance and durability of an innovative thermochromic solution (TS) applied to hot mix asphalt (HMA) by analyzing its optical-thermal properties and resistance to environmental degradation. Outdoor experiments conducted over a 12-hour summer day demonstrated that the functionalised HMA achieved surface temperature reductions of 5–9°C during peak solar radiation periods compared to the control HMA. Accelerated weathering tests revealed a notable decrease in solar reflectance, with a reduction of 32% observed after 24 h of exposure. Despite this loss, the TS continued to demonstrate cooling potential. The findings provide a scientific basis for the application of TS pavements, addressing urban climate change strategies and enhancing resilience.