Effect of CFBC ash as partial replacement of PCC ash in alkali-activated material

Abstract

The present study investigates the effect of partial replacement of conventional pulverized coal combustion (PCC) fly ash with circulating fluidized bed combustion (CFBC) ash in alkali activated material. The alkali activated material was produced by using sodium hydroxide (4M, 5M and 6M) and sodium silicate solution. The characteristics of alkali activated materials were assessed by evaluating compressive strength, along with microstructure and physiochemical properties. A strong correlation was observed between the mole concentration of sodium hydroxide and compressive strength of alkali activated materials containing CFBC ash. The microstructural and physiochemical results revealed that the calcium rich CFBC ash significantly affects the formation of polymerization products. A hybrid form of polymerization product was formed which resulted in densified microstructure. Furthermore, higher molarity of sodium hydroxide can unlock the polymerization potential of CFBC ash. The findings also revealed that incorporation of lower amount of CFBC ash is an efficient way to reduce the formation of sulfoaluminates in alkali activated materials incorporating CFBC ash.