A novel gypsum-based lightweight composite: a combined investigation of technical and self-cleaning properties

In recent years, the focus in building facades has been on the development of self-cleaning ability in building environments for environmental remediation. However, other technical properties must not deteriorate in order to gain self-cleaning ability. Assessing other technical requirements along with self-cleaning performance, for which such studies are very limited, may reveal their potential under real conditions more clearly. This study presents the production and detailed characterization of self-cleaning gypsum-based lightweight composite materials. The main goal of this study was to evaluate both self-cleaning abilities and other technical characteristics (physical, mechanical, and particularly thermal and acoustic) of this type of composite building materials together. In this study, nano-sized anatase TiO2 was added to the composite structures at different ratios (0, 1, 2.5, 5, 7.5, 10, 15, and 20 wt.%, based on the replacement of anhydrite binder) to obtain photocatalytic activity. The results reveal that even at low ratios such as 1 and 2.5 wt.%, the incorporation of TiO2 provides a high contribution to the self-cleaning effect. In addition, some technical features also improve at these levels, and some of them remain almost the same as the TiO2-free control specimen or within the standards. It has been determined that the use of TiO2 increases the porosity of the composites, thus improving the thermal and acoustic properties. In addition, the compressive strength of the specimens improved up to the usage level of 2.5% TiO2. It was also confirmed that the excess of TiO2 had a negative effect on self-cleaning as well as other technical properties. Additionally, the possible reasons for the unexpected decrease in photocatalytic rate (19.6 x 10(-3) min(-1)) after 10 wt.% TiO2 ratio, which enables the highest photocatalytic activity, has been also explained in this study.