Application of Fly Ash in Production of Hollow Concrete Block

Abstract

Now days, hollow concrete blocks and bricks are becoming very popular. These blocks are being widely used in construction of residential buildings, factories and multi-storied buildings. The material used to produce hollow concrete block different from place to place depend on the availability of material. At Ayika Addise textiles and investment group used Coal as alternative for energy recourses to produce textiles at sebeta zone around alemgena. So that To prevent fly ash from entering the atmosphere the company used power plants machine to gather it and keep it from being carried with the exhaust gases out of the stack and used for production of HCB as construction material. Using fly ash by partial replacement of cement for production of HCB indirectly reduce environmental pollution. The main objective of this study was to compare the compressive strength of hollow concrete blocks with and without fly ash. Specifically it focused in determining workability with and without fly ash, the compressive strength of both blocks, to compare the cost of production and to determine the optimum replacement of fly ash for ordinary port land cement. This experimental study was conducted by preparing two types of HCB test samples. The first test sample of HCB was produced by using mix proportion 1:3:2:1 of cement, sand, crushed aggregate 00 and crushed aggregate 01 respectively as a control group. The second sample HCBs were produced with fly ash by using cement, sand, crushed aggregate 00 and crushed aggregate 01. The ratio of cement to aggregate used was 1:6. Out of one part of cement the fly ash was replaced with 10%, 15%, 20%, 25% and 30%, amounts of fly ash by mass. According to this study, the fly ash amount which gives a higher strength was achieved at 10%, 15%, 20%, 25% and 30% of fly ash content respectively, which was comparatively the compressive strength of HCB decrease as replacement of fly ash increase. Even though the result was satisfy the requirement of a higher compressive strength for load bearing hollow concrete block. The production cost of HCBs with fly ash was found lower than the HCB without fly ash. Depend on workability; fly ash concrete has low workability than a conventional Portland cement concrete as shown on the discussion and as the percentage of fly ash increase the workability was decrease. The study further recommended to the micro and small HCB producers to increase the production of HCB with fly ash, for the contractors and clients of Alemgena to use this product.