New Approach to Recycle Glass Cullet in Asphalt Shingles to Alleviate Thermal Loads and Reduce Heat Island Effects

摘要

As an approach to mitigate the harmful effects of urban heat islands (UHI), the use of glass cullet in the production of asphalt roof shingles has the potential to be employed as a cool roof strategy. The objective of this study was to test the hypothesis that the use of recycled glass cullet increases the solar reflectance index (SRI) without affecting the performance of asphalt roof shingles. In order to evaluate the feasibility of using recycled glass cullet in this new application, the engineering properties of glass cullet were measured and compared to conventional aggregates used in the production of asphalt roof shingles. Laboratory shingle specimens were then prepared in order to measure solar reflectance properties and strength characteristics of conventional and recycled glass roof shingles. Results show that while the use of recycled glass cullet as a replacement to standard ceramic coated black roofing granules on the top surface of asphalt shingles increased the SRI, the addition of white pigment powder (anatase ultrafine titanium dioxide [TiO_2] particles passing mesh #320) to the surface granules greatly improves the reflectance properties of the roof to a level that meets the cool roof threshold.