A novel solar reflective coating with functional gradient multilayer structure for cooling asphalt pavements

摘要

Solar reflective coating is an effective way to reduce the surface and internal temperature of asphalt pavements. Existing coating is limited by its single-layer structure, and its development has persistent challenges, highlighting a need to study novel coating with high cooling efficiency, safety and durability. In this paper, a solar reflective coating with functional gradient multilayer structure was designed, named FGMC. It consisted of three different functional layers arranged in a gradient from top to bottom, including a near-infrared transmission layer, a strong reflection layer and an insulating bonding layer. The key pigments or fillers used in each layer were determined by utilizing an indoor irradiation test. The optimal dosage of pigment G, pigment Y, titanium dioxide and floating beads was 3.7%, 3.7%, 15.2% and 16%, respectively. The cooling effect of the proposed coating was investigated by comparing the surface and internal temperature of the coated and uncoated asphalt mixture specimens. Results showed that the strong reflection layer contributed the most to cooling effect, reducing temperature about 8.5 degrees C-9.5 degrees C. The internal temperature of specimens coated with FGMC used pigment G and pigment Y decreased by 11.5 degrees C and 13 degrees C respectively. Moreover, the skid resistance, water resistance, alkali resistance and abrasive resistance of the proposed coating met the requirements of standards. The proposed coating can reduce temperature and provide a new direction for solar reflective coating of asphalt pavements. (C) 2019 Elsevier Ltd. All rights reserved.