Self Cleaning Geopolymer Concrete (SCGC) Using Industrial By-Products - A Comparison Review

Concrete is widely used material next to water in the world. It stands as 3^rd largest emitter of the Carbon dioxide (CO₂) which is greenhouse gas that contributes to global warming. Geopolymer Concrete is a distinct concrete, which will not use Portland cement in its preparation significantly reducing the carbon footprints. Geopolymer concrete is an eco-friendly concrete as it is made by using industrial by-products (i.e. fly ash, metakolin and silica fume etc.) that have alumina and silica content, and the problem of disposal of these industrial wastes which pollutes the land can also be resolved. Geopolymer binder is made by mixing sodium silicate (Na₂SiO₃) and sodium hydroxide (NaOH) or potassium silicate (K₂SiO₃) and potassium hydroxide (KOH) in required quantity with the above industrial by-products. Further, by adding photo catalytic substances like Titania (TiO₂) and Zinc oxide (ZnO) to the concrete it develops the ability of self-cleaning. The concrete with self-cleaning capacity will energise the photo catalysts by using UV (Ultra-violet) radiation from Sun light thus by accelerating organic particles decomposition through oxidation reaction. As a result, it is possible to keep building surfaces clean and minimise air pollution. This paper reviews the effect of various ashes like rice husk ash, baggasse ash and bottom ash etc. in partial or full replacement of fly ash and ground granulated blast furnace slag (GGBS) in geopolymer concrete to make it suitable for many applications with the identified gaps and future scope. The existing literature supports the use of SCGC in place of conventional concrete not only due to lesser environmental impacts associated but also due to better waste utilisation and resource conservation in the SCGC.