Foamed Geopolymers as Low-Emission Insulating Materials with CO2 Sorption Capability – Porosity, Thermal Conductivity, and Adsorption Performance

The article presents the results of research on foamed geopolymer materials as potentially dual-function building materials, combining thermal insulation properties with the ability to physically adsorb carbon dioxide. The materials were developed on the basis of fly ash, using hydrogen peroxide as a foaming agent. Two variants of the foaming agent quantity were used to assess how this quantity affects the type of porosity, thermal insulation, and CO₂ adsorption capacity. The porous structure was characterised using mercury porosimetry and physical CO₂ adsorption. A full analysis of their insulating and accumulating properties was also carried out. Measurements of the thermal conductivity coefficient (λ) showed that these materials have low thermal conductivity (in the range of 0.101 W/m·K), which confirms their suitability as ecological building insulators. At the same time, sorption tests performed using a physical sorption analyser confirmed the ability of selected composites to adsorb CO₂, with a noticeable influence of porosity parameters depending on the amount of blowing agent used on the efficiency of the process. An unexpected result of the research was the conclusion that a smaller amount of foaming agent may be more beneficial in terms of CO₂ adsorption capacity, while maintaining similar insulation parameters. The results suggest that properly designed foamed geopolymers can serve a dual function – as insulation materials and passive CO₂ adsorbents, thus supporting efforts towards sustainable development and decarbonisation of construction. The results obtained provide a basis for further in-depth analyses related to the possibility of using foamed geopolymers as carbon dioxide-absorbing materials.