Development of Lightweight Building Materials Using a Sustainable Chemistry Approach: The Multifunctional Effects of Garlic Husk Ash on Foam Concrete

In this study, the application of garlic husk ash (GHA) as a new form of biomass-related pozzolanic material that could be used as a partial replacement of cement in the production of foam concrete was examined. GHAs added to cement were equal to 0-30 wt %. The impact of GHA on various properties tested (i.e., mechanical strength, durability, thermal conductivity, and microstructure) demonstrated that GHA is a silica, low-calcium material. Adding GHA increased the initial and final set times by up to 56 and 52%, respectively. As water demand increased, workability declined. Despite the decrease in early age compressive strength, later-age strength improved due to pozzolanic activity. At 90 days, the GHA30 mix's compressive strength reached 12.80 MPa, slightly exceeding that of the control mix. Insulation properties improved as thermal conductivity decreased by 18% to 0.199 W/m·K. After 50 freeze-thaw cycles, the GHA25 and GHA30 mixes maintained up to 87% of their compressive strength, demonstrating exceptional freeze-thaw resistance. In high-GHA specimens, SEM analysis confirmed the development of a denser microstructure with increased C-S-H gel. The outcomes indicate that GHA, as an abundant biomass byproduct, enhances the long-term durability of lightweight concrete while minimizing the environmental footprint associated with cement utilization. This research promotes the integration of agricultural biomass residues into construction materials to improve circular economy principles and foster the development of sustainable, energy-efficient infrastructures.