The use of iron oxide in asphalt mixtures to reduce the effects of urban heat islands

Aiming to ensure greater well-being of the population, the aim is to mitigate the accumulation of heat in urban centers, which is intensified by the phenomenon known as Urban Heat Island (ICU), which is characterized by the increase in urban temperatures in comparison to rural areas, due to the dark color and the low reflectivity of the paved surfaces. To minimize such an impact, it is suggested to use materials that absorb less heat. This explains, the choice for incorporating iron oxide in asphalt mixtures, in red and yellow pigments, with the purpose of increasing the asphalt reflectivity and consequently reducing heat absorption. To meet these objectives, the following steps were taken: first, mechanical characterization of the mixtures with the incorporation of iron oxide (red and yellow pigment), to verify the resistance of these mixtures after the addition of the pigment, and second, to verify whether the addition of pigments significantly reduces temperature and increases the reflectivity of the surface. The results indicated the technical feasibility of incorporating iron oxide into the mixture, allowing to increase in the useful life of these mixtures. Comparing conventional and colored mixtures, there was a reduction in the surface temperature of the coatings and an increase in solar reflectivity. •The following steps were taken in this study: first, mechanical characterization of the mixtures with the incorporation of iron oxide, to verify the resistance of these mixtures after the addition of the pigment (yellow and red), and second, to verify whether the addition of pigments significantly reduces temperature and increases the reflectivity of the surface.•The addition of iron oxide increased the stiffness of the asphalt mixture, improving its performance to rupture, traction and permanent deformation.•A temperature reduction of up to 2.7 °C was obtained for the mixture with the red pigment when compared to the reference mixture.•The asphalt mixture with red pigment showed an increase in albedo by 18.8% in relation to the reference mixture.•The asphalt mixtures can be used in heavy traffic zones and in regions with high temperatures in summer, allowing greater resistance to traffic and greater reflectance of the pavement.