A study of fine aggregate replacement with fly ash an environmental friendly and economical solution

The use of fly ash as a replacement of sand has a great potential to benefit our society in terms of reducing demand of natural sand, reducing environmental problems, conserving energy and reducing landfill area requirement. This paper presents an approach to increase the utilization of fly ash and conserve scarcely available natural sand for sustainable development. The experimental investigation by the inclusion of fly ash as a partial replacement of sand as compared to control cement mortar mixes indicated 50% to 100% increase in the compressive strength of mortar at 91 days. Replacement of 50% sand with fly ash can save about 0.4 m3 sand. Comparison of cost per N/mm2 compressive strength has shown about 40% to 60% saving in cost. Based on the experimental results, correlations are developed for finding out the compressive strength and cost at 28 and 91 days. Sand was replaced with 10% to 50% of fly ash by weight and 0.5, 0.55, 0.6 and 0.65 W/C ratios were used. Flow test performed for mortar revealed that as the percentage replacement of sand with the fly ash increased the flow of the mortar decreased. It was also observed that wet and dry densities were more than the control mortar for 10% & 20% replacement of sand with fly ash but for higher replacement percentage density reduced marginally.