Effect of Material Composition on Strength Characteristics of Fly ash Bricks by Harsimranjit Singh
Bricks are one of the oldest material used in construction industry. Commonly used bricks are made up of clay with certain admixtures. Due to rapid increase in population and to meet its needs, new houses and multi-storey building are constructed in large numbers, which requires large number of bricks for its construction. Thus due to overuse of clay bricks a new material is required to be used for construction of bricks. Fly ash is one of the industrial waste, produced from thermal power plants and which is dumped in open environment and causes environment pollution. As it contains silica which reacts with lime and strengthen the brick, therefore it can be used for construction of bricks. In the present study fly ash bricks were made by using fly ash, sand, lime and Plaster of Paris (POP) in different mix proportions. The brick specimens of size 230 x 110 x 70 mm were manufactured and various quality parameters like compressive strength at an age of 7 and 28 days, water absorption and dry density were tested. The economical mix design of the fly ash bricks for maximum compressive strength and its rate analysis was also done. The results show that strength decreases with increase in fly ash content and increases with increase in sand and lime content in fly ash bricks. Water absorption value increases with increase in fly ash content and decreases with increase sand and lime content in fly ash bricks. Dry density decreases with increase in fly ash content and increases with increase in sand and lime content in fly ash bricks. The maximum compressive strength was obtained for mix percentage of fly ash-38%, sand-33%, lime-24% and POP-5%. Thus it is imperative that fly ash be used purposefully and fly ash bricks provide a good solution.