Cellular lightweight high calcium fly ash geopolymer concrete containing basalt fiber cured at ambient temperature

This study investigated cellular lightweight high-calcium fly ash geopolymer concrete incorporating basalt fibers and cured at ambient temperature. Foam was incorporated at 0–6% by weight, while basalt fiber was added at 0–6% by weight of fly ash. The compressive strength, density, water absorption, porosity, thermal conductivity, and sound absorption were evaluated. The results demonstrated that foam content played a dominant role in reducing density and thermal conductivity, whereas an appropriate basalt fiber content improved the mechanical performance of the cellular lightweight geopolymer concrete. The mixture containing 4% basalt fiber and 3% foam exhibited the optimum performance for structural lightweight concrete applications, achieving a compressive strength of 38.3 MPa at a density of 1691 kg/m³. For masonry applications, increasing the foam content to 6% produced a substantially lower density of 1119 kg/m³ while maintaining a compressive strength of 6.32 MPa. Furthermore, the Strength-Density-Cost-Carbon Performance Index (SDCC-PI), based on strength–density efficiency, material cost, and GHG emissions with equal weighting after ASTM-based screening, was used to identify suitable mixtures for different applications. The SDCC-PI results confirmed that the optimum mixture depends on the intended application and the required balance among mechanical, physical, economic, and environmental performance. Overall, the developed cellular lightweight geopolymer concrete demonstrates potential as an ambient-cured lightweight construction material with favorable mechanical, thermal, and acoustic properties.