Use of Fly Ash as Supplementary Fine Aggregate in OPC Concrete

Abstract

Fly ash, generated during the combustion of coal for energy production, also found as residues in electrostatic precipitators is an industrial by-product, which is recognized as an environmental pollutant of great concern. Because of the environmental problems presented by the fly ash, considerable research has been undertaken on the subject worldwide. The use of fly ash, a secondary market material created through the generation of electricity from coal, offers more sustainable alternative by reducing the amount of consumed Portland cement, which has many benefits, improves concrete performance in both the fresh and hardened state and use is also cost effective. By utilizing fly ash in concrete and other products, architects, engineers and regulators express a commitment to promote sustainable growth with waste utilization and exercising responsible building practices.

In the present study an investigation has been carried out on use of fly ash as fine aggregate replacement for production of concrete using Portland Pozzolana Cement (PPC).  Concrete mixes having mix proportion of 1: 1.68: 3.32 (cement: sand: aggregate) with water cement ratio (0.50) were used for the investigation.Compressive strength tests were conducted at 7 and 28 days for assessment of strength development. The results indicated that there is substantial increase in strength of concrete when the replacement level of fly ash is increased upto 40% and thereafter on increase of fly ash the strength starts decreasing.  The water absorption was found to decrease with reduction in water cement ratio and aggregate cement ratio and also with increase in fly ash.