Durability Properties of Geopolymer Concrete and its Application in Civil Engineering Field

Abstract

Concrete usage around the world is second only to water. Ordinary Portland Cement (OPC) concrete is the most popular and widely used building materials, due to availability of the raw materials all over the world, its ease in preparation and fabrication in all sorts of conceivable shapes. About 1.5 tons of raw materials is needed in the production of every ton of OPC. Amount of carbon dioxide released during the manufacturing of Ordinary Portland Cement (OPC) due to the calcinations of limestone and combustion of fossil fuel is in the order of one ton for every ton of OPC produced. On the other hand, the abundant availability of fly ash worldwide creates opportunities to utilize this by-product of burning coal, as a substitute for OPC to manufacture concrete. It is essential to find alternatives to make environment friendly concrete. An alternative to make environmentally friendly concrete is the development of Inorganic alumina-silicate polymer, called Geopolymer, synthesized from materials of geological origin or by-product materials such as fly ash that is rich in silicon and aluminum. According to Davidovits, geopolymerization is a geosynthesis that chemically integrates materials containing silicon and aluminium. During the process, silicon and aluminum atoms are combined to form the building blocks that are chemically and structurally comparable to those binding the natural rocks. By using the fly ash based geopolyer concrete addresses the two environmental related issues i.e. the high amount of carbon dioxide released to atmosphere during production of OPC and utilization of Fly ash. Experimental work includes design mix of M25 grade of geopolymer concrete by various permutations and combinations in fly ash content. So that comparison of various durability studies and behaviour of reinforced geopolymer concrete specimen can be compared with M25 grade of control concrete. Class F fly ash is used as source material. Geopolymer concrete has been heat cured for 24 hours at 750C.Sodium silicate and Sodium hydroxide solution is used as alkali activators. Durability study includes Sulphate Resistance, Acid Resistance, Chloride Attack, Water Absorption, Sorptivity and Accelerated Corrosion Test. For sulphate, acid and chloride, performance of the concrete is evaluated based on visual appearance, change in mass and change in compressive strength, resepctively. Sorptivity and water absorption characteristic are also evaluated. Accelerated corrosion test performed to evaluated corrosion resistance property of geopolymer concrete. For reinforced geopolymer concrete specimen, load carrying capacity, load-deflection relationship, mode of failure and crack pattern are observed and compared with control concrete. Test results have indicated that geopolymer concrete posesses good durability resistance. An acid resistance test result shows very low mass loss of geopolymer concrete after various exposure period as compared to control concrete. Sulphate and chloride resistance also indicates good resistance of geopolymer concrete with no significant change. Water absorption and sorptivity of geopolymer concrete found low compared to control concrete. Accelerated corrosion test confirm that the corrosion resistance of geopolymer concrete is better than control concrete. Reinforced geopolymer concrete beam and column results for various parameters like load carrying capacity, load deflection relationship and failure mode were found similar to control reinforced concrete specimen.