Performance Evaluation of Alkali Activated Fly Ash Lightweight Aggregates

Abstract

The potential use of fly-ash obtained from thermal power plant for producing artificial lightweight aggregate has been systematically investigated in this study. Use of processed artificial aggregates from industrial wastes instead of natural aggregates can significantly reduce the cost of concrete production. Flyash has been used in concrete either as supplementary cementitious material or as fine aggregate substitution. This study deals with the use of flyash as aggregate by means of artificial production using pelletization process. The influence of alkali activator on the production and strength enhancement was studied. Also, the properties of alkali- activated aggregate using various binder materials such as cement, bentonite, metakaolin and blast furnace slag were studied. Moreover, the study emphasizes the efficient production of cold-bonded fly-ash aggregate using cement, bentonite, furnace slag and metakaolin. Mechanical strength properties of various fly-ash aggregate were tested for crushing strength and impact strength. The investigation results suggested that the cold-bonded fly-ash lightweight aggregate using slag showed a highest crushing strength of 22.81 MPa and also exhibited lower water absorption of 13.01%. The influence of binary blends of flyash and a binder was observed to be an important parameter for achieving a high strength aggregate.