A Study on the Preparation and Performance Optimization of Alkali-Activated Fly Ash-Based Aerogel-Modified Foam Concrete

To address the energy-saving requirements of ultra-low energy consumption buildings in hot summer and cold winter regions, high-performance foam concrete(FC)was developed using fly ash(FA) as the sole silico-aluminous raw material using alkali-activation technology. A mix proportion calculation model was established based on the volume method to accomplish the preliminary design of the material system, and orthogonal tests were employed to achieve the synergistic enhancement of thermal, mechanical, and other relevant properties. Innovatively, the introduction of the 2.5 wt% SiO2 aerogel reduced the thermal conductivity to 0.1107 W/(m·K). To mitigate the high water absorption of FC, internal mixing with a sodium methyl silicate solution (at a concentration of 8%) controlled the mass water absorption by 3.87%. Test results confirmed that the optimized FC exhibited a dry density of 576.34 kg/m3, compressive and flexural strengths of 5.83 MPa and 1.41 MPa respectively, a dry shrinkage rate of only 0.614 mm/m, and strength and mass loss rates below 10.5% and 1.8% after freeze-thaw cycling. This material integrates ultralow thermal conductivity, excellent hydrophobicity, and structural stability, thereby providing a novel solution for the envelope structures of low-energy consumption buildings.