Aging albedo model for asphalt pavement surfaces

One of the most significant factors affecting pavement-induced Urban Heat Islands is the albedo. Several studies have shown albedo's effect on air temperature and building energy usage. Albedo depends on the optical properties of the material constituents of the surface layer of the pavement, which can change over time or with additives. The albedo of a series of full-scale asphalt and concrete pavement test sections of varying ages in Rantoul, Illinois (USA) was measured and a non-linear aging albedo model for asphalt pavements was developed. For a hypothetical pavement section, the current practice of assuming a constant albedo over time was found to overestimate the Global Warming Potential of the asphalt pavement by about 25%. In addition, the albedo of translucent polymer fibers was determined to be 0.07 using a spectrophotometer. This does not have a thermal impact on the pavement as long as the fibers remain coated with cement paste. However, if the fibers become exposed because of abrasion, they will have an impact on albedo depending on the pavement area containing exposed fibers.