Performance of concrete made using sintered fly ash lightweight aggregate-a review

Abstract

Current work summarizes research done on potential of sintered fly ash lightweight aggregate based concrete and its suitability as an aggregate. The manuscript presents physical and chemical parameters of ingredients such as fly ash as well as binders adopted in manufacturing process covering effect of these materials on parameters related to pelletization like duration, angle of inclination and rotation speed and its subsequent effect of aggregate characteristics. The impact of sintering temperature and its duration on aggregate characteristics is also discussed. The physio-chemical and mechanical characteristics of sintered fly ash aggregate is briefly presented. The review of literature suggests that specific gravity and water absorption of sintered fly ash lightweight aggregate is low and high respectively as compared to conventional aggregate. The use of additives such as alkaline activators, styrene-butadiene rubber, quick lime etc. and additional treatments such as coating or vacuum impregnation has shown potential for reducing water absorption. The mechanical performance of sintered fly ash lightweight aggregate in concrete is different from normal concrete. Factors affecting compressive strength, flexural strength and modulus of elasticity apart from the characteristics of manufactured sintered fly ash lightweight aggregate are cement content, supplementary cementitious materials, additives used, treatment done to aggregate, aggregate content, shape index of aggregate etc. Studies have indicated no direct relationship between factors affecting concrete durability such as water absorption, mechanical perfromance, cement content, water penetrability and freeze-thaw resistance of sintered fly ash lightweight concrete.