<p>This study utilises ultra-fine sand from the Yellow River sediment in the preparation of autoclaved materials. To address the issue of low reactivity in silica sand, waste glass and MgO are employed as modifiers to enhance the strength of autoclaved materials. Multiple characterisation methods are used to illustrate the mechanisms in terms of hydration products and microstructure. The results demonstrate that the amorphous silica from waste glass has a positive impact on hydrothermal reactions but impedes the formation of tobermorite. Replacing 20% of quartz sand with waste glass significantly improves the compressive strength of autoclaved material by balancing the formation of hydration products and tobermorite. The incorporation of MgO further enhances the compressive strength of autoclaved material. However, its effect on tobermorite formation and morphology is negligible, and there is an increase in the porosity of the autoclaved material. The improvement effect of MgO should be primarily derived from the enhanced mechanical properties of Mg-doped hydration products. Additionally, at an excessive MgO replacement ratio, MgO cannot fully participate in the hydrothermal reaction and thus exists in the form of Mg(OH)₂. In summary, combining 20% waste glass and 5% MgO yields the most favourable synergistic effect, improving the compressive strength of quartz sand autoclaved materials by over 50% and the utilisation efficiency of raw materials.</p>