Characterizing thermal behaviors of various pavement materials and their thermal impacts on ambient environment

摘要

As the development of urbanization, more and more underlying surfaces in urban areas are covered with artificial pavements, which are recognized as one of the major origins that deteriorate the thermal environments for living. In this study, the thermal behaviors of the pavements with various paving materials and their impacts on the thermal conditions of the surrounding environment were investigated with specially designed laboratory simulation tests. Four commonly used paving materials, traditional Portland cement concrete (PCC), Portland cement porous concrete (PCPC), dense-graded asphalt concrete (AC), and open-graded friction course (OGFC), were considered for the study. The testing results showed that, under the solar radiations during daytime, the pavements made with asphalt mixtures and open graded mixtures normally absorb more radiation and exhibit higher temperatures than the pavements made with cement concrete and dense-graded mixtures, respectively; however, they reflect less radiation back to the surroundings and resulting in lower air temperatures near the pavements, which could to some extent mitigate the thermal discomfort on the nearby human and buildings. During nighttime, compared to concrete pavements the pavements made with asphalt mixtures would emit more heat to the surroundings as a thermal source and elevate the ambient temperature. Under windy conditions, the pavements paved with open-graded mixtures manifest remarkable benefits in alleviating the thermal impacts on the environment compared to conventional dense-graded pavements, because the wind could accelerate the thermal exchange between their porous surfaces and the above air, and thus reducing the temperature of the pavements. Moreover, during nighttime, the temperatures in the open graded pavement could also be declined rapidly with the enhanced convections on its porous surface and present lower temperature than that of the atmosphere, consequently improving the cooling effectiveness of the pavement on the surrounding environment. (C) 2017 Elsevier Ltd. All rights reserved.