Strength Development of Fly Ash by Lime and Gypsum Addition for its Effective Utilization-A Laboratory Investigation

In India approximately 70% of power generation has been through coal-fired thermal power plants. About 60% of produced coal is used for power generation. The coal which is used in power plants has an ash content of about 30-50%. Because of this high ash content, the generation of fly ash in India stands at around 118 million tons per annum. It is estimated that the fly ash generation will touch 175 million tons by 2012 occupying huge land area in addition to throwing environmental and social problems. At present the utilization of fly ashes in India is about 35 %. An effective mechanism for bulk utilization of fly ash is to fill low lying or mine void areas with strength enhancing methodology. The pH stabilization technique is a method to increase the pozzolanic property of the fly ash and hence strength of it. This paper analyses some of the physical and chemical properties of fly ashes procured from two different sources. In addition their strength enhancing characteristics have been evaluated through lime and gypsum addition. The study optimizes those Class-F fly ashes with respect to their lime content and compressive strength.