Synthesis and characterization of self foaming geopolymer for enhanced thermal barrier applications

Abstract: In response to growing demands for sustainable construction materials, this study presents the development of self-expanding geopolymer foams utilizing industrial silica fume and natural zeolite tuff. These materials, chosen for their availability and high reactivity, were activated with sodium hydroxide solutions of varying concentrations and cured at different temperatures. The development of a porous structure was driven by the release of water vapor, generated as a result of the elevated temperatures caused by the exothermic reaction between aluminosilicates and concentrated alkali solutions. The resulting foams exhibited excellent thermal insulation properties, with thermal conductivity values ranging from 0.14 to 0.31 W/m·K, and compressive strengths between 3.3 and 13.3 MPa. A comprehensive microstructural characterization, including X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), Fourier transform infrared (FT-IR) spectroscopy, and image-based porosity analysis, revealed the formation of homogeneous pore structures, influenced by both alkali activator concentration and curing temperature. The study highlights the critical role of mixture design and processing conditions in optimizing foam morphology, density, and mechanical performance. By recycling industrial by-products and minimizing energy input during curing, this study highlights a possible way for producing eco-friendly insulation materials with strong potential for application in energy-efficient buildings. Highlights: Self-foaming geopolymer was synthesized using silica fume and natural zeolite. NaOH concentration and curing temperature governed pore structure and properties. Optimized foams show low thermal conductivity (0.14 W/m·K) and 13.3 MPa strength. High porosity (61–74%) and low density (0.65–0.86 g/cm³) achieved by vapor expansion. Sustainable, low-energy process converts industrial by-products into thermal insulators.