Study on the effect of sintered secondary aluminum ash prepared pottery sand on the mechanical properties and ecological performance of high-strength cement-based materials

To reutilize secondary aluminum ash and heavy metal sludge, this study investigates the impact of pottery sand content and its pre-wetting state, making by sintering all of the solid waste mentioned above, on the workability, mechanical properties, and leaching content of harmful substances in high-strength concrete, combing Micro-CT, XRD, DTG, FTIR, and SEM to analyze its mechanism. The results show that the incorporation of pottery sand in the high-strength concrete matrix accelerates the cement hydration process and enhances its early strength. The pre-wetted pottery sand with a content of 10 % and the drying pottery sand with a content of 30 % exhibit superior performance, with 3-day compressive strengths increasing by 15.95 % and 14.18 %, respectively, compared to the group without pottery sand. As the content of pottery sand increases, the compressive strength of the specimens first increases and then decreases. When the content is below 20 %, the pre-wetted pottery sand group demonstrates better strength than the drying pottery sand group, the effect is more remarkable while pottery content is beyond 20 %. At the same time, the pre-wetting manner significantly limits the migration and penetration of harmful ions. Microanalysis reveals that the active silicate and aluminate element in the pottery sand consume Ca(OH) 2 from the hydration products, generating more calcium silicate hydrate (C-S-H) gel, which refines the pore structure, making it more compact. The maximum pore volume for the reference group, pottery sand group, and pre-wetted pottery sand group were 4.76 mm³ , 2.87 mm³ , and 2.65 mm³ , respectively. • A comprehensive study on the impact of pottery sand on mechanical properties. • An in-depth exploration of the mechanism by which pottery sand affects high-strength cement-based materials. • A systematic evaluation of the environmental risks associated with the use of pottery sand.