Manufacture of Geopolymer Artificial Aggregates by Pelletization and Crushing Processes

Abstract

Aggregates are an important ingredient of concrete. They are of two types: coarse aggregates and fine aggregates. The supply of natural aggregates on Earth is declining with technological advancement, hence, alternatives to natural aggregates are needed. Artificial aggregates have been manufactured using a coal burning waste, i.e. fly ash. On mixing fly ash with an alkaline activator, the mixture reacts and hardens. Aggregates are manufactured either by mixing materials using a granulator pan or by crushing materials using a stone crusher. The optimal manufacturing method was determined by comparing physical properties, such as bulk specific gravity, water absorption, and aggregate hardness, of the aggregates manufactured using these two methods with those of natural coarse aggregates. The average bulk specific gravity was 1.776 and 1.857 for the aggregates produced by the pelletization and crushing processes, respectively, and 2.957 for the natural aggregates. The average water absorption values were 11.62% and 8.37% for the aggregates produced by the pelletization and crushing processes, respectively, and 4.17% for the natural aggregates. The average aggregate hardness values, determined using the Los Angeles abrasion test, were 27.33% and 25.98% for aggregates produced by the pelletization and crushing processes, respectively, and 24.05% for the natural aggregates.