Exploring Cool Asphalt Pavement Technologies: A Field-Based Experimental Analysis of Temperature, Reflectivity, and Thermal Comfort

Urban heat islands (UHIs), intensified by global warming, significantly impact environmental quality and public health. Cool pavements mitigate these effects by lowering surface and ambient temperatures. This study evaluates the thermal performance, reflectivity, and pedestrian-level thermal comfort of four asphalt pavement technologies under real-world conditions. Field experiments at a controlled testing site in Vienna, Austria, combined long-term monitoring and focused 1-day measurement campaigns following an extended dry period under cloudless and calm wind conditions. Four pavement variants, porous asphalt (PA8), light-colored asphalt concrete (AC8-Light), reference asphalt concrete (AC8-Ref), and yellow-pigmented asphalt concrete (AC8-Yellow), were instrumented with temperature sensors, pyranometers, globe thermometers, and thermal cameras to capture surface, subsurface, and air temperatures, solar reflectance, and thermal comfort indices. AC8-Yellow consistently exhibited the lowest surface and subsurface temperatures, up to 9.5°C cooler than PA8, owing to its higher albedo. Field albedo values ranked AC8-Yellow (0.229), AC8-Light (0.188), AC8-Ref (0.155), and PA8 (0.106). AC8-Yellow’s field value fell well below its laboratory benchmark (0.46) after 1 year. However, AC8-Yellow also produced the highest near-surface air temperatures and physiological equivalent temperature, suggesting increased pedestrian heat load from reflected radiation. AC8-Ref and AC8-Light exhibited similar thermal behavior, suggesting aggregate color is not a major factor after 1 year of use. PA8’s porous structure did not provide cooling benefits under dry conditions, acting as a thermal insulator instead. The findings underscore the complex trade-off between pavement surface cooling and pedestrian comfort, highlighting the necessity for site-specific strategies to optimize UHI mitigation.