Temperature of Paved Streets in Urban Mockups and Its Implication of Reflective Cool Pavements

Precast Concrete Pavements of High Albedo to Achieve the Net “Zero-Emissions” Commitments

Pavements store heat, which is subsequently released into the atmosphere, heating the surrounding air. Therefore, this process contributes to climate change and global warming. For this reason, the use of high-solar-reflectance (albedo) pavements is seen as one of the potential mitigation methods for climate change. Concrete pavements have a much higher albedo than asphalt due to their light gray color compared with black pavements. Accordingly, the widespread utilization of highly reflective concrete pavements will improve local climate change mitigation. Nevertheless, concrete albedo slightly decreases over time because of weathering. Albedo and solar reflectance index (SRI) measurements were taken on actual precast concrete pavements made with different mixes. The methodology applied for this project is based on the comparison between the asphalt and concrete pavements’ reflectivity. Conventional concrete mix designs can provide cool pavements with SRI higher than 29. Replacement of black pavements by highly reflective concrete pavements appeared to be a cost-effective and easily implemented measure to combat climate change. Finally, multidisciplinary studies considering factors such as building materials’ albedo, among other mitigation measures, should be performed to provide more precise and reliable guidance to policymakers, stakeholders, decision makers and urban planners.

Effect of Precast Concrete Pavement Albedo on the Climate Change Mitigation in Spain

The widespread use of solar-reflective concrete pavements can mitigate climatic change and urban heat islands (UHI) by cooling the pavement surfaces that are made of concrete instead of asphalt. The methodology that was followed is based on the comparison between the asphalt and concrete albedo effects in a specific application and area. In this study, we found that a reduction of temperature in the terrestrial surface, equivalent to the removal of 25–75 kgCO2/m2, could be achieved. Considering all the motorways and freeways of Spain, which is the third country in the world in km, a yearly equivalent carbon dioxide emissions reduction of 13–27 million tons could be reached. This value is quite high considering that the cement sector worldwide released about 2.9 Gigatons of carbon dioxide in 2016. Therefore, there is a positive balance in the use of concrete pavements. Furthermore, concrete is a material completely recyclable at the end of its service life and concrete pavement construction requires local resources, avoiding GHG emissions due to transport. An increase in the Spanish freeway network albedo by replacing asphalt pavements with concrete ones will improve the local climate change mitigation.