Gap-Graded Concrete Blended with Rice Husk Ash and Fly Ash

Fly ash is increasingly used on a worldwide scale in cement and concrete because of reduced cost, material and energy savings, and improved resistance and durability of the fly ash concrete. One of the drawbacks of (Class F) concrete is its potentially relatively low early strength. Highly reactive pozzolanas such as silica fume and metakaolin can be used to enhance the properties of fly ash concrete. However, silica fume and metakaolin are relatively scarce and expensive. Rice husk is an active pozzolana produced by controlled burning of rice husks, hitherto an agricultural waste. This paper describes the combined use of rice husk ash (RHA) and fly ash in high-performance concrete. The high-performance concrete was based on a gap-graded concrete aggregate with fine sand. Further, a superplasticizer was applied. These ternary blended cement concretes showed greater strength gain than the fly ash concrete.