Use of sodium metasilicate as silica source and stabilizing agent in two-part metakaolin–H2O2 geopolymer foams

• Published in: Construction & building materials Vol. 391; p. 131907
• Main Authors: dos Santos, Maria Natali Gomes, dos Santos, Cassiana Mendonça, de Souza, Marcelo Tavares Gomes, de Vasconcelos, Elder Alpes, da Nóbrega, Ana Cecília Vieira, Marinho, Érika Pinto
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 08.08.2023
• Subjects: 3D computed tomography; Foams; Geopolymer; H2O2; Pores; SiO2/Al2O3; Foams; Geopolymer; SiO2/Al2O3; Pores; H2O2; 3D computed tomography
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2023.131907

[Display omitted] •Sodium metasilicate was used as a complementary silica source in two-part geopolymer foams.•Sodium metasilicate acted as a stabilizing agent in H2O2–geopolymer foam.•H2O2 should be limited to a SiO2/Al2O3 ratio up to 2.5 for curing at 50 °C.•SiO2/Al2O3 = 2.5 and H2O2 = 6.0% were most conducive to the porous structure.•Produced geopolymer foams can be used as lightweight insulating cores. The synergistic effects of the SiO2/Al2O3 ratio (2.0, 2.5, and 3.0) and H2O2 content (1.5%, 3.0%, and 6.0%) were evaluated in metakaolin-based geopolymer foams using sodium metasilicate pentahydrate as a complementary silica source. Sodium metasilicate helped to stabilize the pores in foams with SiO2/Al2O3 molar ratios of up to 2.5 cured at 50 °C without stabilizing additives. The optimum porous system for insulation cores was obtained using a SiO2/Al2O3 ratio of 2.5 and H2O2 content of 6%. Furthermore, a SiO2/Al2O3 molar ratio of 3.0 reduced pore formation as the increased geopolymerization and viscosity served as a barrier to bubble diffusion.