Dark, heat-reflective, anti-ice rain and superhydrophobic cement concrete surfaces

Abstract

Antifouling, weatherable, and heat-reflective coatings have much value for solar sheltering of building in summer. In this work, a multifunctional cement mortar mixture was obtained by mixing “cool cold” black pigments with cement, sand, TiO2 nanoparticles and water. After the mixture was mortared on a cement concrete slab, dried at room temperature and treated with fluorine silicon sol, a gray cement concrete layer was obtained. UV–visible-infrared spectrometer confirmed that the layer has obvious infrared-reflective property at 780–2500 nm. Under the radiation of a 275 W and 40 cm height infrared lamp, the surface temperature of the gray “cool cold” cement concrete is about 40 °C lower than that of the carbon black cement concrete, and is about 20 °C lower than that of the ordinary cement concrete, and is only about 1 °C higher than that of the white TiO2 cement concrete. Moreover, all these cement concrete surfaces showed typical superhydrophobic (SH) property and the “cool cold” cement concrete surface further exhibited stable SH properties to both rain and UV radiation, which may allow for self-cleaning performance for the surface and the ability to retain its heat-reflective property over a long period of time. Meanwhile, the “cool cold” cement concrete SH surface exhibited excellent anti-ice rain performance. Because the layer can be easily mortared on the cement concrete substrate, we think it would have great potential for use on building roof and outside walls to reduce air-conditioning energy consumption in the summer.