Self-Cleaning Mortar Façades with Addition of Anatase and Rutile Titanium Dioxide for Cool Façades

Abstract

The concern with the best energy performance of buildings is a current theme, and construction materials that bring improvements to the performance of buildings and their surroundings are in demand. Façades play a crucial role in regulating the temperature within buildings by permitting or obstructing the transfer of heat and also affect the ambient temperature. Light-colored façades help maintain environments with milder temperatures, but pollution, rain, and other degrading agents darken the colors of the façades, reducing their capacity of sunlight reflection. In this scenario, the present study analyzed the addition of different types of titanium dioxide, anatase and rutile, in cement tiles for building façades, combining the ease and speed of assembly with the self-cleaning effects of photocatalysis. The 1 cm thick tiles were produced with a 1:3 mortar ratio (cement:sand/dry aggregate) with a 0.5 water:cement ratio and the addition of 0.3% polypropylene fiber. Different admixture levels (0%, 5%, and 10%) of rutile and anatase titanium dioxide were used. The samples were tested for flexural strength, absorption, permeability, and photocatalysis effect by observing the color change and surface characteristics of the boards using a spectrophotometer. In addition, the hygroscopicity was analyzed through a water drop, using a goniometer. The results obtained showed that cement tiles with 5% titanium dioxide, which influences the color variation of the tiles, meet the regulatory requirements for use in outside environments. Thus, these materials have the potential to be used as cool façades since, by keeping their color lighter, the materials can reflect sunlight, therefore keeping lower temperatures inside the building, and, consequently, minimizing the heat island effect.