An overview of the properties of sustainable concrete using fly ash as replacement for cement

Many industries produce several types of by-products in a large amount each year which is negatively affecting the environment by compromising human health and depleting the natural resources. Utilisation of such industrial by-products in the construction field has become an important step to address the environmental problems as well as to solve the waste disposal crisis. Fly ash (FA) is one of such by-products obtained from pulverised coal combustion in thermal power plants. FA can be utilised as substitution or addition of cement in making cement-based products. This paper critically analyses and summarises the influence of FA on characteristics of concrete. The physical, chemical properties of FA and its hydration reaction mechanism have been addressed in the present study. The influence of FA on the fresh and hardened properties such as workability, compressive and tensile strength, modulus of elasticity and durability characteristics like resistance to abrasion, permeability, chloride penetration, carbonation, sulphate attack and alkali silica reaction, freezing and thawing effect and shrinkage in concrete have been reviewed in this paper.