Durability evaluation of heat-reflective coatings for road surfaces: A systematic review

•Identified key factors influencing durability of heat-reflective coatings.•Durability loss reduces cooling effect by 13 %–53 % and reflectance by 50 % in a year.•Outlined future research recommendations for durable heat-reflective coatings.•Extending lifespan of heat-reflective coatings beyond one year is crucial. To mitigate urban heat islands (UHI), heat-reflective pavement coatings reflect solar radiation, significantly cooling urban surfaces. However, their effectiveness is compromised by tire abrasion, environmental aging, soiling, and UV irradiation, leading to polymer degradation and decreased cooling efficiency. This paper reviews durability aspects of heat-reflective pavement coatings, focusing on methods to assess durability, the effects of durability on optical performance and temperature reduction efficiency, and the literature on developing durable coatings to extend lifespan. Through systematic review, this study highlights how UV exposure, high temperatures, moisture, chemical pollutants, and physical abrasion degrade coatings, underscoring the importance of selecting durable coating materials. Studies indicate that durability loss significantly diminishes the cooling effect of coatings, reducing it by 13 % to 53 % after series of weathering and abrasion testing, while reflectance decreases by up to 50 % after one year. The review suggests future research should focus on formulating coating materials that are UV-nonabsorptive and resistant to abrasion and soiling. Additionally, it recommends examining spraying techniques, maintenance practices, and the need for standardized testing to accurately evaluate the durability of heat-reflective coatings. Despite the potential of these coatings to mitigate UHI effects, the challenge of extending their lifespan beyond one year remains critical.