Effects of secondary aluminum ash sintered ground powder on properties of calcium sulfoaluminate cement-based grouting materials

To mitigate the cost of utilizing calcium sulfoaluminate (SAC) cement-based grouting materials and alleviate the environmental impact of heavy metals and harmful elements in secondary aluminum ash, this study investigated the effects of different secondary aluminum ash sintered ground powder (AP) dosages on the workability, mechanical properties, volume stability, and environmental compatibility of SAC grouting material. Results indicated that incorporating 15 % yielded the most optimal comprehensive performance. Specifically, the initial setting time and early compressive strength of SAC grouting material exhibited an initial increase followed by a decrease with escalating AP dosage. In contrast, the long-term compressive strength gradually declined with higher AP dosage. Microscopic analyses revealed that AP addition introduced more aluminum phases, facilitating SAC hydration and enhancing the generation of AFt and Al(OH)3, thereby improving the pore structure. The SAC grouting material demonstrated effective stabilization of four heavy metals (Pb, Cr, Zn, and Cu) present in AP. Further elemental analysis revealed that fluorine (F) primarily existed in the grouting material containing AP as CaF2 and AlF3, while nitrogen (N) was present as AlN and NH3.