Preparation and Performance of a Low-Carbon Foam Material of Fly-Ash-Based Foamed Geopolymer for the Goaf Filling

Abstract

The treatment of goaf subsidence is important for sustainable development. Geopolymer is a new type of cementing material with excellent mechanical properties, durability, corrosion resistance, and other advantages owing to its unique three-dimensional spatial aggregation structure. Herein, a type of preparation technology of fly-ash-based foamed geopolymer suitable for goaf filling was developed by adding a chemical foaming agent to the matrix of fly-ash-based geopolymer. The mechanical properties, chemical composition, and pore structure characteristics of the samples were discussed. When the samples with different contents of fly ash, sodium metasilicate, sodium stearate, H2O2, and NaOH were prepared, a uniaxial compression test was performed to analyze the uniaxial compression failure characteristics and compression strength of the samples. The mineralogical composition of each sample was analyzed by X-ray diffraction (XRD) test, and the microstructure images of different samples were observed using scanning electron microscopy (SEM). The effects of the content of each component on the properties of the samples were discussed. Finally, the CO2 emission, energy consumption, and cost of producing fly-ash-based foamed geopolymer were analyzed. Overall, the material had the advantages of low energy consumption, low CO2 emission, environmental-protection ability, and waste utilization and thus has a broad application prospect in treating subsidence.

Study of In Situ Foamed Fly Ash Geopolymer

“…Benefiting from their unique configuration, geopolymers possess advantages when compared to OPC, including better mechanical properties and durability; lower permeability; better resistance to heat, acid, and freeze-thaw; and lower heavy metal leaching content [20]. Furthermore, the synthesis of geopolymers does not need high-temperature treatment, and the CO 2 emission is much less than that of OPC [21,22]. Such properties make geopolymers robust candidates for use as sustainable construction materials.…”