Effect of Replacement of GGBS and Fly Ash with Cement in Concrete

Use of ordinary Portland cement as a binding material is well accepted for construction purposes globally. The huge demand for cement in construction leads to a rise in the use of absolute energy from the cement industry and high CO₂ emissions. As a result, the global cement sector is facing increasing difficulties in the conservation of material and energy resources, as well as decreasing its CO₂ emissions. Similarly, many industrial wastes like fly ash, ground granulated blast furnace slag, waste recycled product, cement kiln dust, silica fume, quarry dust, glass waste, rubber waste, red mud are generated nowadays due to growth in industrialization, increasing urbanization and rising standards of living due to technological innovation, which is leading to harmful threats to the environment along with the waste disposal problem. Therefore, in this paper efforts have been made for not only to control environmental pollution but also to reduce the cost of waste management and concrete production by utilizing ground granulated blast furnace slag (GGBS) and fly ash (FA) with partial replacement of cement. Industrial wastes, such as GGBS and FA, are waste by-products from iron industry and thermal power plants, respectively. In the present study, these by-products at different percentages as a partial replacement of cement have been utilized in concrete. The tests were conducted with partial replacement of GGBS at different percentages of 0, 10, 15, 20 and 25% and with FA at different percentage of 0, 5, 7.5, 10, 12.5 and 15% by the dry weight of cement. Tests on workability and compressive strength were carried out on concrete mixes prepared at different percentages of GGBS and FA. The experimental results show a significant improvement in the strength with increase in GGBS and FA content in partially replaced cement-concrete, making it viable for practical uses in the building industry. On the basis of experimental results, it is concluded that with an increase in GGBS and fly ash percentage the compressive strength of concrete increases and the evaluation allows the design of GGBS and FA mixed concrete for medium strength concrete.