Partially Replacing Sand with Coal Bottom Ash and Cement with Metakaolin– A Review

Objective: In order to follow the ecological trend, the utilization of alternate materials in construction industry is a growing interest. This review shows the effects of incorporation of coal bottom ash and metakaolin on the fresh and hardened properties of self compacting concrete. Methods: For fresh properties slump cone, L-Box, U-box, J-ring and V-funnel were used. In order to find out the mechanical properties, tests were done on compression testing machine and flexure testing machine. Scanning electron microscope and X-ray diffraction techniques have also used in order to study the microstructure of self compacting concrete having coal bottom ash and metakaolin. For durability properties, tests like sorptivity, water absorption and Rapid Chloride Permeability Test (RCPT) were done. Finding: Utilization of a material which is otherwise a waste is of great significance. Coal bottom ash which is a waste product of thermal power plants can be utilized in self compacting concrete to partially replace natural sand. Likewise metakaolin has a potential to partially replace cement in Self Compacting Concrete (SCC) in order to reduce the consumption of ordinary portland cement, manufacturing of which is quite hazardous to the environment. This paper presents the findings of various researchers who have studied the effect of using coal bottom ash and metakaolin in self compacting concrete. Based on these studies it has been found out that coal bottom ash has a size almost similar to that of natural sand and pozzolanic activity of metakaolin is quite high. Throughout this paper, impact of coal bottom ash and metakaolin on fresh and hardened properties of self compacting concrete are reviewed and optimum percentage of replacement is also analyzed based on the basis of practical approach. Application: Coal bottom ash and metakaolin can be effectively used to partially replace natural sand and cement in self compacting concrete. Introduction of these two materials in SCC leads to an economical and environment friendly concrete. Construction with demand of high compressive, split tensile and flexural strength can be achieved by incorporation of these materials.