Properties of geopolymerised low-calcium bottom ash aggregate cured at ambient temperature

Abstract

This paper discusses the factors influencing the pelletization and properties of lightweight aggregate using bottom ash through alkali activation and curing at ambient temperature. The experiments were designed using central composite design of Response surface methodology. The alkaline activators used for the synthesis of geopolymer aggregate are NaOH and Na2SiO3. Ca(OH)2 has been used along with the alkaline activators to facilitate hardening of the geopolymer aggregate at ambient temperature. The influence of various factors and their interaction effects on the pelletization efficiency, bulk density, ten percent fines value, open porosity and water absorption on geopolymer aggregate cured at ambient temperature were identified. Addition of Ca(OH)2 resulted in the increase in pelletization efficiency. The molarity of NaOH and dosage of Ca(OH)2 enhanced the TPFV. The open porosity and water absorption of the aggregate reduced considerably with an increase in NaOH molarity and Na2SiO3/NaOH ratio.