Utilization of Waste Lime Sludge and Coal Fly Ash in Construction Industry

Large quantities of industrial by-products are produced every year in India and across the globe. These materials have dual problems of disposal and health hazards. By-products such as coal fly ash and sludge from water treatment plants require greater attention since the magnitude of impact on the environment such as land, surface and ground water resources and air is high, if not properly disposed of. One solution to this crisis lies in recycling waste into useful products in the construction activities to replace the natural materials such as soil and conventional products such as cement wherever possible which will lead to reduction in the economic and environmental problem of waste disposal and also conserve the depleting resources. The aim of this paper is to find the reuse potential of water softening sludge and coal fly ash in the construction industry. In this study, a composite material has been formulated using fly ash and lime sludge with replacing cement to make mortar specimen. The compressive strength of the formulated mix was determined by performing an unconfined compressive strength test. The optimum content of cement, fly ash and sludge was found to be 20%, 40%, 40%, respectively, thereby reducing the cement content to a great extent. It was then observed that the strength of the optimum mix invariably increased 31% by proportionately replacing cement with fly ash and sludge which was dependent on the curing technique used. Oven-dried samples had higher strength than lime water cured samples.