Indoor and Outdoor Aging Behaviors of a Heat-Reflective Coating for Pavement in the Chongqing Area

Abstract

The indoor and outdoor aging behaviors of a heat-reflective coating were studied regarding the problems derived from aging and reduced cooling effects. A one-year natural exposure test of the coating on a roof and on concrete samples was conducted, and a 28-day xenon lamp aging test on concrete and cylindrical samples was carried out. Surface appearance, infrared spectrum, cooling value, and reflectivity changes in different aging periods were analyzed. The results show that the amount of solar radiation is a key factor in aging. Aging can cause a gradual increase in carbonyl content and thus lead to a decrease in resin light transmittance, given that the carbonyl group absorbs visible light and infrared rays easily. This results in a reduction in reflectivity and cooling value. Reflectivity and cooling value show a linear relationship in the indoor and outdoor aging process. With respect to reflectivity and cooling value, solar radiation has a downward quadratic parabolic tendency whereas xenon lamp radiation maintains a linear relationship. By comparing the results of the indoor and outdoor aging tests, it can be concluded that aging for 32.0 days under accelerated conditions is equivalent to aging for one year under natural exposure conditions in the Chongqing area.