The effect of aluminium reaction on formation mechanism and structural properties of geopolymers

One of the chemical foaming agents which is widely used for making lightweight geopolymer concrete is aluminium powder. On the other hand, aluminium is one of the important elements of geopolymer gel and the role of aluminium in early and later development of geopolymer structure is well-known. There are many studies on the application of aluminium foaming agent for making lightweight geopolymers regardless of the effect of this foaming agent on the chemistry of the lightweight material. In this paper, the geopolymer formation mechanism with and without aluminium powder is studied and the impact of aluminium reaction on geopolymer formation and its structural properties is investigated. It seems that the sample with aluminium foaming agent starts the geopolymerization reaction quicker. Also, the sample with Al foaming agent developes better microstructure, and the final strength of this sample is also higher.