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 infraredreflective property at 780–۲۵۰۰ 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.

Introduction

Due to the rapid increase of building energy consumption, which accounts for nearly approximately one-third of total societal energy consumption [1], it is important to seek some effective methods to realize building energy saving [2,3]. Recently, enhancing the infrared reflectance of the exterior wall or roof has been studied and adopted to solve this problem, because the infrared energy accounts for approximately half of the total solar energy [4]. So far, white or light color coatings [5,6] have been widely applied on the exterior of building walls or roofs because it is well known that white color possesses the best solar reflective performance [7]. However, the white or light color always has the problem of being easily polluted and single color, hardly satisfies human demand in actual building decoration. In recent years, more and more deep color pigments which possess excellent infrared reflective property have been developed, such as blue [8], yellow [9], red [10] and so on.