A mineral-based approach to cool asphalt pavements: Results from a field experiment

Source abstract

The Urban Heat Island (UHI) effect intensifies climate change challenges in cities, with asphalt pavements contributing significantly due to their low solar reflectivity and high heat retention. We conducted a comparative field experiment to quantify the cooling performance of reflective asphalt pavements in which the mineral fraction of the wearing course was fully replaced by highly reflective ground calcium carbonate (GCC) aggregates to increase pavement solar reflectance (albedo). Seven test sections (including untreated references) based on two asphalt mixtures and three types of post-laydown treatment were installed in a parking lot in Egerkingen, Switzerland, and monitored over one summer season in a real-world setting. Results indicate that embedded GCC aggregates significantly increase pavement albedo and reduce surface temperatures by up to 5°C relative to the reference section. Across the tested configurations and conditions, we observed an approximately linear relationship between albedo and surface temperature, corresponding to an average cooling of ∼6°C per 0.1 increase in albedo. This on-site validation provides evidence-based performance quantification for a GCC-based, structurally integrated cool pavement approach and supports its potential as a scalable option for reducing pavement surface temperatures.