Reflective–evaporative semi-flexible pavements for urban thermal regulation

Urban pavements influence heat exchange between transport infrastructure and the surrounding atmosphere, yet how surface evolution alters their cooling performance remains unclear. This study investigates the reflective–evaporative cooling of water-retentive semi-flexible pavements with progressively exposed aggregates. Controlled polishing, optical–thermal characterization, outdoor monitoring, mechanical evaluation, and ENVI-met simulation were integrated to link surface evolution with pavement and street-canyon thermal response. Aggregate exposure increased albedo to 57.8% for limestone and 47.4% for granite, whereas diabase and basalt remained optically constrained. Relative to SMA, the proposed pavements reduced peak surface temperature by up to 11.01 °C; each 10 percentage-point albedo gain corresponded to a 0.67 °C reduction. Street-canyon simulation predicted a near-ground air temperature decrease of up to 1.07 °C. Granite provided a favorable thermal–mechanical balance, suggesting aggregate selection as a practical pathway for heat-mitigating urban pavement design.