Potential Use of Fly Ash for Developing Angular-shaped Aggregate

The prices of aggregate are increasing in India due to the massive demand for natural aggregate for infrastructure development. An attempt has been made to check the feasibility of the past developed technique for developing angular-shaped light-weight fly ash coarse aggregate from three different types of fly ashes. In this study, the effects of binder content, water content and hot water bath curing temperature on the compressive strength of blocks, as well as the impact value of prepared aggregate for fly ash-binder mixes were investigated. A relationship between impact value and compressive strength has also been suggested to predict the impact value of fly ash aggregate based on the compressive strength of block. For making angular-shaped fly ash aggregate, it was found that the fly ash with CaO content of 0.71%-3.85% requires higher binder content and curing temperature than that required for fly ash with CaO content of 10.45%. The resulting lightweight aggregates from three fly ashes have a compacted structure and angular shape for good interlocking. The results of mechanical properties test showed that the aggregate also meets the criteria of Indian code specifications for structural concrete aggregate.