How does aluminium foaming agent impact the geopolymer formation mechanism?

Abstract

Aluminium is widely used as a foaming agent in lightweight geopolymer concretes. The impact of aluminium reaction on the phase evolution of fly-ash based geopolymers is investigated. In-situ Fourier transform infrared spectroscopy (FTIR) is used to track the changes in the nanostructure of geopolymers. By combining the FTIR functional group analysis with Atomic-force microscopy (AFM) results, it is possible to evaluate the phase development during the early hours of reaction. At the initial stages of geopolymerization, aluminium reaction induces the formation of aluminium hydroxide gel which precipitates on fly ash and conceals the reactive surface of ash particles. Therefore, the dissolutio..