A comparative study of the utilization of synthetic foaming agent and aluminum powder as pore-forming agents in lightweight geopolymer synthesis

Lightweight geopolymer concrete was synthesized using fly ash as an aluminosilicate source with the addition of a pore-forming agent. The synthesis of a geopolymer was conducted by employing various volume ratios of geopolymer paste to the foaming agent: 1:0.50, 1:0.67, 1:0.75, 1:1.00, 1:1.33, 1:1.50, and 1:2.00, while the ratios of aluminum powder weight percentage to the fly ash weight varied between 0.01 - 0.15 %wt. The results showed that the higher foaming agent content, the lower the compressive strength and density of the geopolymer. The ratio of the geopolymer paste to the foaming agent, 1:1.33 was found to produce the strongest light weight geopolymer whose compressive strength and density were 33 MPa and 1760 kg/m³, respectively. With the addition of 0.01%wt aluminum powder, the geopolymer specimen showed the highest compressive strength of 42 MPa and density of 1830 kg/m³, respectively. X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and FT-IR were utilized to study the effects of foaming agent and aluminum powder addition onto the microstructure, surface morphology, and functional groups of the geopolymer. Both types of synthesized geopolymers have the potential to be developed in terms of compressive strength and density in the future.