Determination of optimized geopolymerization factors on the properties of pelletized fly ash aggregates

This research investigates the effect of geopolymerization factors on the pelletization in the production of artificial fly ash aggregates. The proportion of pelletized fly ash aggregate mixes was designed through Taguchi's L9 orthogonal array. The properties of the aggregates produced from the optimal mixes were characterized according to the standard specifications. The effect of geopolymerization factors such as Na2O content, water content, and curing regime on the properties of the pelletized fly ash geopolymer aggregates was determined through response indices at the age of 14, 28 and 56 days. In addition, Grey relation based analysis was performed to identify the most critical parameter for optimization among three geopolymerization factors selected in this investigation, for the production of pelletized fly ash geopolymer aggregates. It is observed from the response indices and Grey relation results that the impact value of the aggregates and crushing strength of individual pellets is governed by heat curing and high water content at the age of 14 and 28 days. However, at the age of 56 days these response indices are significantly governed by the solution curing and high water content. It was also noted that the minimum Na2O content of 3.5-4.5% is adequate for the production of pelletized fly ash aggregates.