Properties and Characteristics of Lean Concrete Made with Recycled Coarse Aggregate and Fly Ash

Abstract

Qualitative aggregates have become scarce and expensive in various places in India, due to rapid enhancement in infrastructure activities essential for the development of new construction facilities. The use of waste materials in construction appears to be an attractive proposition because of their low cost, environmental considerations and depleting source of quality aggregates, if good performance can be ensured through appropriate technology. The problem of disposal of waste generated from building demolition and infrastructural deterioration is a cause of worry for ecology & environment. Many research, investigations and solutions have been evolved, developed and explored for this particular environmental problem and the best solution found is recycling. As is in the rest of the world, as a result of fast population growth and urbanization, the construction industry is growing at a great pace in our country as well. Everyday old buildings are being knocked down and replaced with the new ones. The debris from these demolished buildings is thrown away, causing environmental pollution, or is used as filling material. Thermal power stations using pulverized coal as fuel produce enormous quantities of ash as waste products of combustion. In India, it is estimated that thermal power plants produces about 100 million tonnes of fly ash per annum. Hence the problem of ash disposal is expected to become acute due to the limited space available for ash disposal near most of the thermal power plants. At present, percentage utilization of fly ash is only around 15 to 20%. Generally, fly ash is used as replacement of cement, as an admixture in concrete and in manufacturing of cement. An effort has been made to increase the utilization of fly ash by using it as a partial replacement material for fine aggregate in concrete because in current scenario the use of fly ash is limited and restricted.