Evaluation of Synthetic Aggregate from Lignite Fly Ash

This paper deals with the burning of various combinations of pelletized fly ash, agglomeration agents, and additives to make a synthetic aggregate. Several methods of agglomerating and burning the fly ash pellets, including rotary kiln and sintering grate, were investigated. The aggregates produced were evaluated in terms of their technical potential for use as a structural quality aggregate. Major conclusions reached are: (1) high quality, nonbloated, synthetic aggregate can be made from either the rotary kiln process or the sintering grate process; fly ash aggregate properties meet or exceed the properties of the commercially produced lightweight aggregate in all respects except unit weight; and (2) concrete made from the fly ash aggregates investigated should provide more than adequate strengths and suitable durability. Furthermore, these concrete strengths exceed those made with the commercial lightweight aggregate.