Lightweight non-autoclaved foam concrete: effects of microsilica and microcalcite on structure and performance

This study presents a lightweight non-autoclaved foam concrete with a target dry density of approximately 500 kg/m 3 and improved compressive strength. The proposed composite binder system includes microsilica, microcalcite, and a polycarboxylate-based superplasticizer. The novelty lies in the combined use of microsilica and microcalcite as a dual modification system: microsilica promotes additional C-S-H formation and matrix densification, while microcalcite improves particle packing and stabilizes the closed-pore structure. After 28 days, the developed foam concrete achieved a dry density of 505±10 kg/m 3 , compressive strength of 4.6 MPa, thermal conductivity of 0.12 W/(m·K), water absorption of 18 %, and closed pore content of 82 %. The results indicate that the material is suitable for lightweight structural and thermal-insulating applications. Its reduced density is also beneficial for energy-efficient and seismic-resistant construction. A preliminary economic and environmental assessment indicates the potential advantages of the proposed composition.