Denver-based High Concrete Group has introduced a mix design that is said to significantly improve the heat reflectance of precast concrete surfaces, causing them to stay cooler by reversing the urban heat island effect. The mix imparts a solar reflective index (SRI) of 82 in finished products, nearly double that of the company’s conventional gray concrete mixes.
High Concrete developed the mix design using 75% white cement and 25% ground granulated blast furnace slag for the cementitious content. Central-eastern Pennsylvania limestone aggregates provide a neutral-colored base. The SRI of 82 was achieved on a form-finished white concrete block sample. The high-SRI concrete mix is available for specification in High Concrete Group’s architectural precast concrete wall panels.
High solar reflectance precast helps buildings reflect rather than absorb solar radiation, supporting the sustainable design goals of project teams working in new commercial, institutional, and other construction. The solar reflectance of a building’s exterior surfaces impacts its contribution to the urban heat island effect, a phenomenon in which built areas are dramatically warmer than surrounding rural areas, resulting in poorer air quality and increased utility costs.