Mitigation of Urban Heat Island Effects by Thermochromic Asphalt Pavement

Abstract

Asphalt road pavements are usually dark and, consequently, have a low albedo. Therefore, they absorb energy as heat, increasing the Urban Heat Island (UHI) effect, which impacts the environment, energy consumption, and human health. Through the functionalization with thermochromic materials (TM), this work aims to develop a smart asphalt pavement able to change its surface color, increasing the reflectance, and thus mitigate this phenomenon. To achieve this goal, asphalt substrates were functionalized by a surface spray coating of a thermochromic solution (TS) containing aqueous solution of thermochromic microcapsules (thermocapsules), dye, and epoxy resin. To evaluate the functionalization features, Fourier Transform Infrared Spectroscopy (FTIR), and Thermal Differential test (TDT) with cyclic temperature variation were performed in the functionalized asphalt binder. Moreover, Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectrometry (EDS), a Quick Ultraviolet Accelerated Weathering Test (QUV) with Colorimetry test, and an adaptation of the Accelerated Polishing Test (APT) were performed on the functionalized asphalt mixture. The results indicate that the functionalization of asphalt substrates with TS exhibits a reversible color-change ability, higher luminosity values when subjected to temperatures above 30 °C, and wear resistance.

Smart Asphalt Mixtures: A Bibliometric Analysis of the Research Trends

“…UHI refers to the phenomenon where an urban is significantly warmer than its adjacent rural areas due to human actions. To minimize this issue, using thermochromic asphalt mixtures offers not only greater mechanical strength and increased resistance to aging for the pavement but also provides the capability to reduce heat absorption by changing their color [38][39][40]. In this sense, it is possible to impart better properties to the material since the black color of conventional asphalt roads absorbs a high percentage of sunlight, increasing its surface temperature and contributing to the warmer conditions in urban areas [39,41].…”