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.

This study investigates the effects and mechanisms of three mineral admixtures—fly ash (FA), silica fume (SF), and metakaolin (MK)—on the fresh, mechanical, and microstructural properties of Yellow River sediment (YRS)-based shotcrete. A comprehensive experimental program was conducted, including setting time determination, workability assessment, and mechanical strength evaluation, complemented by microstructural characterization using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The results indicate that the incorporation of FA prolonged initial and final setting times and improved pumpability but reduced build-up thickness and compressive strength; splitting tensile strength at later ages remained comparable to the control. SF shortened the final setting time and reduced flowability but enhanced shootability, layer build-up, and medium- to later-age compressive and tensile strengths, with an optimal dosage of 5%. MK accelerated the final setting time, slightly reduced early-age compressive strength, but improved early-age splitting tensile strength and achieved 28-day compressive strength comparable to the control. Microstructural analyses revealed that FA participates in pozzolanic reactions forming C–(A)–S–H gel, while SF and MK promote the formation of dense C–S–H and carboalumination phases, enhancing matrix densification. Based on performance evaluation, the recommended dosages are FA ≤ 20%, SF ≤ 15%, and MK ≤ 15%. These results establish clear links between macroscopic performance and microstructural evolution, providing experimental guidance for the sustainable development of YRS-based shotcrete.