Albedo of Pervious Concrete and Its Implications for Mitigating Urban Heat Island

Abstract

Urban heat islands have become a growing concern in many cities around the world. Pervious pavements have been proposed as a potential solution to mitigate this effect, but their effectiveness in reducing surface temperatures is still uncertain. This experimental study aims to investigate the reflectivity of pervious concrete to determine whether pervious pavements are cooler than conventional pavements. To achieve this, five different Portland cement concrete mixes are used to create pervious concrete samples with varying porosity levels. The samples are sliced, and their spectral reflectance and albedo are measured and analyzed. The results showed that the albedo of dry pervious concrete decreases linearly with increasing porosity. Pervious concrete with a wet surface exhibits an albedo of approximately 0.15 which is independent of porosity. Additionally, fresh, dry pervious Portland concrete has an albedo ranging from 0.20 to 0.35, which is 0.10 to 0.20 lower than conventional fresh cement concrete. As a result of this low albedo, caution should be exercised when developing pervious concrete as a solution to combat the urban heat island effect, unless measures are taken to increase evaporation and offset the additional solar absorption resulting from the low albedo. Overall, these findings suggest that the use of pervious pavements alone may not be sufficient to reduce surface temperatures in urban areas. Future research should explore ways to increase the albedo of pervious pavements and develop effective strategies to mitigate the urban heat island effect.