Characteristics of lightweight fly ash aggregates produced with different binders and heat treatments

This study investigated characteristics of lightweight fly ash aggregates with various binders produced by different heat treatments. Different amounts of binders were mixed with fly ash and put into the pelletization disc. Bentonite and glass powder were used as binders at 0%, 5% and 10%, individually, and in combination at 7.5% each, by weight of fly ash. The pellets thus produced were then sintered at temperatures of 1100, 1150 and 1200 °C. Specific gravity, water absorption, porosity and crushing strength of these aggregates were determined. The properties and microstructure of aggregates were modified by different sintering agents and heat treatments. The strength and specific gravity of all aggregates decreased with increasing the binder content (disregarding binder type) at the highest temperature. Aggregates with low water absorption and high strength and specific gravity can be attributed to the dense structure with discontinuous and small size pores. Increasing binder content reduced water absorption at all temperatures.