Experimental evaluation of rheological, optical, and thermal properties of a thermochromic synthetic binder based on a light-coloured matrix

Asphalt pavements are highly susceptible to solar radiation, causing excessive surface temperatures and accelerated high-temperature distress. This study developed a thermochromic synthetic binder based on a light-coloured matrix to overcome the optical masking effect of conventional dark asphalt and enhance temperature-dependent solar reflectance. A light-coloured binder was optimised and modified with 0–8 wt% thermochromic powder, and its physical, rheological, thermophysical, optical, and temperature-regulating properties were evaluated. The optimised binder exhibited rheological performance comparable to conventional 90# asphalt, while the thermochromic powder increased thermal storage capacity. More importantly, the light-coloured matrix significantly enhanced the optical response of the thermochromic material, resulting in substantially higher solar reflectance than conventional thermochromic asphalt. Outdoor and indoor tests demonstrated delayed heating and reduced surface temperatures without compromising mechanical performance. These findings highlight the potential of light-coloured thermochromic binders for mitigating pavement temperatures under solar radiation.