Microstructure and properties of coal-fly-ash-based foam geopolymer

Abstract

Large amount of circulating fluidized bed combustion fly ash (CFA) were generated in power plants.In this paper, foam geopolymer material was prepared using CFA, water glass (WG) and sodium hydroxide (NaOH) as raw material and hydrogen peroxide as foaming agent.By adopting (wt) 3%-8% hydrogen peroxide, the properties of foaming multiple, pore size distribution, apparent density, macro porosity and compressive strength were tested.The balance of foaming driving force and paste resistance and the influence of macro pore structure on compressive strength were studied.The results showed that the balance of the foaming driving force and paste resistance was content of H2O2 (wt) of 5%; and the foaming multiple, apparent density, macro porosity and compressive strength were 4.2, 255 kg/m3, 81.7% and 0.65 MPa respectively when the H2O2 foaming agent(wt) was 5%.The different pore size distribution had different degree of the decrease on compressive strength, the gray correlation degree between compressive strength of samples and pore diameter range of 10-20 μm was the greatest, that was, the range of pore size was 10-20 μm as the key factor, and the effect on compressive strength of samples was the largest.

Keywords

• geopolymer
• foam material
• gray correlation analysis
• pore structure
• compressive strength