Preparation of Portland Cement-Free Autoclaved Aerated Concrete Using Yellow River Sediment

To solve quartz sand shortage and poor mechanical properties of fly ash-based autoclaved aerated concrete (AAC) in traditional production, this study prepared AAC blocks using Yellow River sediment as the main siliceous raw material, combined with slag, quicklime and other additives. Seven sample groups (S1–S7) with different mix proportions were designed by adjusting the water-to-material ratio and replacing some raw materials with quartz sand or fly ash. The results showed that as the water-to-material ratio increased (S1–S4), AAC slurry fluidity improved, but foaming rate and expansion volume showed a non-monotonic trend. With the same water-to-material ratio, the S5 sample had lower bulk density (695 kg/m3) and moderate but favorable strength (4.25 MPa). Microscopic analysis revealed AAC strength mainly derived from tobermorite and C-S-H gel, and xonotlite enhanced structural stability. This study provides a feasible method for resource utilization of Yellow River sediment in AAC production, with environmental and engineering value.