Research on the utilization of fly ash will no longer refer the fly ash as a waste material of thermal power plants. Use of fly ash in concrete making, makes the concrete economical as well as durable. The fly ash is being added to the concrete in three ways namely, as partial replacement to cement, as partial replacement to fine aggregates and as admixture. Addition of fly ash to the concrete in any one of the form mentioned above, makes the concrete more workable and durable than the conventional concrete. Studies on fly ash as partial replacement to cement gained momentum as such replacement makes the concrete economical. In the present study, an attempt has been made to understand the effects of fly ash on the workability characteristics and strength aspects of fly ash concretes. In India major number of thermal power plants is producing low calcium fly ash. Hence in the present investigation low calcium fly ash has been used. Fly ash in concrete was considered for the partial replacement of cement. The percentage replacement of cement by fly ash varied from 0% to 40% at regular intervals of 10%. More over the fine aggregate to coarse aggregate ratio also has been varied as 1:1, 1:2 and 1:3. The workability tests revealed that up to 30% replacement of cement by fly ash in concrete mixes water demand for reduces, beyond 30% replacement of cement by fly ash demanded more water content for constant workability.

{"references": ["V. M. Malhotra, \"CANMET Investigations dealing with high volume fly ash concrete\", Advances in Concrete Technology, Canada Communication Group Publishing Co., Otowa,Canada,1992, pp 443-470", "R. H. Elmuth. \"Fly ash in Cement and Concrete\", Portland cement Association, 1987.", "I. A. Smith, \"The design of fly ash concretes\", Proc Institute of Civil Engg., vol.33, 1967, pp 769-790.", "K. Ganesh Babu and G. Siva Nageswara Rao, \"Efficiency of fly ash in concrete\", Cement and Concrete Composites, 15(1993) pp 223-229", "B.H. Bharat Kumar, R. Narayanan, B.K. Raghu Prasad and D.S. Ramachandra Murthy, \"Mix proportioning of high performance Concrete\", Cement and Concrete Composites, 23(2001) pp 71-80.", "DIN 1045. Belton und Stahlbeton, GMBH, Koln."]}