Experimental study on alkali modified fly ash coarse aggregate in structural concrete

Abstract

Concrete is a construction material that is mainly composed of cement, fine aggregates, coarse aggregates, and water. The demand for the concrete increase as the infrastructure increases. The use of concrete is increasing day by day which in turn increases the demand of its constituents. Among them is the coarse aggregate, which is one of the most mined materials in the world. The rapid growing construction industry and urbanization pose the need for aggregate increasing steadily. This forces us to increase the number of mining quarries in our planet. This situation is a great danger to the environment. It also accelerates the depletion of our natural resources. In order to reduce the environmental degradation and depletion of natural resources, researchers are in search of alternatives for the constituents of concrete. Many by-products in the world took the place of an alternative to some of the constituents of concrete. Main by-products among them are fly ash, Ground Granulated Blast furnace Slag (GGBS), Silica fume, metakaolin, etc. Fly ash is a by-product obtained from thermal power plants while burning coal as fuel. The fly ash occupies a vast area, and disposal is the main issue nowadays. At present, fly ash finds its way as an ingredient in concrete, bricks, geopolymer concrete, etc. In 1989, Davidovits Suggested a method by engaging fly ash and rice-husk ash or the binders, which can be created by reaction products of polymeric alkaline solutions with silicon and aluminum. These binders are termed as Geopolymers. Palomo et al. (1999) advised that pozzolans such as blast furnace slag may be activated by alkaline solutions to create a binder and replace the use of cement in concrete. In this method, the essential contents to be energized are calcium and silicon in the slag. In the current study, low-calcium fly ash is used to produce Fly ash Artificial Coarse Aggregate (FACA) by the geopolymerization process. Here, the fly ash was obtained from Thermal Power Plant, Mettur, Tamil Nadu.