Strategies for Design and Construction of High-Reflectance Asphalt Pavements

The occurrence of higher air and surface temperatures in urban areas is known as the urban heat island (UHI) effect. Reducing the UHI effect may decrease summer energy use and improve human and ecological health. The Leadership in Energy and Environmental Design certification system has awarded up to three points for construction projects that provide any combination of the following cool pavement strategies for up to 75% of the site landscape: (a) shading hard surfaces on the site with landscape features, (b) using high-reflectance materials with a minimum solar reflectance index (SRI) of 29, and (c) utilizing an open-graded pavement or porous pavement system. Although a guide to the design and construction of porous asphalt pavements has existed for some time, such a guide is not readily available for high-reflective asphalt pavements. The objective of this study is to identify and validate high-reflectance asphalt materials and pavement surface treatments that are suitable for use in parking lots and other large paved surfaces, have a minimum SRI of 29, and are economical. In this study, six technologies exhibited SRI values of 29 or greater: E-Krete microsurfacing, Street-Bond coating, synthetic binder, Densiphalt, and chip and sand seals using light-colored aggregates. Another technology, surface gritting using fight-colored aggregate, most likely would have exhibited SRI values of at least 29 if the aggregate had adhered properly to the asphalt mat.