Application of Nanoscience in Self-cleaning Properties of Concrete Facade for Development of Sustainable Environment

Using mineral admixtures in cement composites as a way to improve their mechanical and sustainable environmental properties is a common practice in concrete technology. Among them Nanosilica effectively influences the composite's early and long-term properties. In this study, the effect of different percentages of TiO2 (0, 2.5 and 5 %) on self-cleaning properties and water absorption of cement composites containing Nano-silica were investigated. According to the use of different cementitious material (Nano-silica) and TiO2 in mix proportions, to obtain mixtures with a desirable workability, superplasticizer was added in different volume percentages. Better size distribution and pore refinement lead to a denser cement matrix with low porosity which in turn considerably the lower water absorption of the cement composites. The maximum final water absorption according to ASTM C497 is 9% for method A and 8.5% for method B. Comparisons of water absorption tests as a result of adding of TiO2 and Nano-silica in concrete show that the maximum final water absorption is 4.9% in N1 design mixture and the minimum final water absorption is 4.3% in N2 design mixture. The incorporation of TiO2 has positively affected the results for Nano-silica containing specimens. A decrease of 6.5% and 11.1% between N1 and N3 respectively shows the positive effect of TiO2 on decrease of water absorption. The results show that TiO2 along with Nano-silica has great potential for improving the environmental and self-cleaning properties of concrete facades of buildings in cities exposed to high levels of cleanliness.