A Critical Review on the Utilization of Fly Ash in Concrete Production

Fly ash, a by-product from thermal power stations, has been used successfully to replace Portland cement up to 30% by mass, without adversely affecting the strength and durability of concrete. In some cases, large volume of fly ash (>40%) is used to achieve the desired concrete properties and lower the cost of concrete production. The fly ash concrete system offers a holistic approach that can help us to achieve the goals of meeting the rising demands for concrete, enhancement of concrete durability with little or no increase in cost (in some instances reduced cost), and ecological disposal of large quantities of the solid waste products from coal-fired power plants. Several laboratory and field investigations involving concrete containing fly ash had reported to exhibit excellent mechanical and durability properties. However, due its conservative nature the construction industry is still not fully utilizing the potential benefits of using fly ash in concrete production. This paper reviews first the origin, properties and current knowledge of fly ash as reported in the literature. This is followed by a discussion on the works done by various researchers on the utilisation of fly ash in concrete production and the potential issues related to their use. Finally, areas of further research have been identified