Study on Eco-Friendly Concrete Blocks without Cement and Curing

Abstract

Cement is the binding agent in concrete and mortar and thus becomes an important construction material. Because of its important and varied use in the rapidly growing construction industry and also its consumption trends in the world makes the production of cement very high. Manufacturing of cement is an energy intensive process and releases approximately equal amount of greenhouse gases into the atmosphere, which affects the earth’s ecosystem. More efforts are being undertaken to conserve energy by means of usage of industrial wastes or by-products, such as fly ash, silica fume, ground granulated blast furnace slag, rice husk ash, etc., containing amorphous silica in its chemical composition, as mineral admixture for partial replacement of cement. Since the cement industry is one of the prime producers of carbon dioxide, creating up to 7% of worldwide man made emissions of this gas, it is necessary to find out complete replacement of cement in construction industry. Geopolymer binder is an innovative construction material and a real eco friendly alternative to conventional cement. Geopolymer binder is a combination of alumina silicate as base material in alkaline solution. The alumina silicate is available in natural minerals as well as industrial by-products. Sodium or potassium silicate and hydroxide mixture forms the alkaline solution. The use of geopolymer binder in concrete can be a great alternative to cement in the construction industry, which will result in saving of energy, environmental protection and conversation of resources. An attempt is made to develop the geopolymer concrete in Oman using low calcium fly ash obtained from India. This investigation consists of three studies. In the first study, development of mix proportions of various grades of geopolymer concrete such as C25, C30 and C40. The mix proportion of geopolymer of various grades obtained based on the mix proportions given in ACI code with hundred percent replacement of cement by fly ash. The compressive strength of geopolymer concrete is achieved by adjusting the concentration of sodium hydroxide in the alkaline solution. The strength of geopolymer concrete is achieved in 24 hours after casting of specimens by heat curing. The results obtained are encouraging and similar to the corresponding strength of cement concrete. In the second study, the developed geopolymer concrete of C25 grade is used to cast the solid block of size 200×200×400mm. In the third study, a beam i.e. prism of size 100x100x500mm with two point loading study was done. The strength properties of the block and the beam are comparable with the strength values of conventional concrete of corresponding grade. Hence, the geopolymer technology can be effectively used in the construction industry in terms of saving energy consumption and resources and ultimately to save the ecosystem of earth.