Analysis of Concrete Block by Partial Replacement of Cement with Fly Ash

Abstract

The objective of this research is to enhance the properties of concrete by using Fly Ash as a partial substitution of concrete. Tests carried out on cement are Initial and Final setting time and on aggregates, specific gravity and sieve analysis. The mean target strength with given compressive strength at 28 day and quality control level is calculated. Concrete blend proportions for the first tryout mix is calculated and casting of cube of 15mm size with curing for 28 days, and then test for strength using UTM/CTM machines. C-S-H gel as well as Calcium hydroxide as bi product when reacts with water. C-S-H gel has an ability to keep the ingredients together by making a proper bond whereas lime which is freely available can react with atmospheric moisture and cause efflorescence. In such cases if we use fly ash, it reacts with free lime and produces C-SH gel again and water as bi product. We have used Fly ash as a partial replacement of cement with variation of fly ash in percentage. In this study fly ash add in increment of 5%, 10%, 15%, 20%, 25%, 30% and 35% replacement of cement which has shown satisfactory results in the strength of the concrete. Fly Ash improved the workability of the concrete, decreases the bleeding, surface finish and increases the cohesiveness. Compressive strength is comparatively increased. The initial strength of concrete with fly ash has lower strength but acquires higher strength after 56 days; which shows that more the nos. of curing days more will be the strength. Thus, it can be used in areas of construction such as dams, pavements etc.