Frost resistance and sustainability of seawater-mixed sintered sludge cement paste

Due to a loose and porous structure, the addition of sintered sludge ash (SSA) in large amounts often leads to a decrease in durability. To address the issue, a systematic investigation is conducted into the combined effects of seawater and SSA (0 similar to 50%) on cement paste. The mixing of seawater enhances the improvement effect of 10% SSA on frost resistance and capillary water absorption. Meanwhile, the seawater-mixed cement paste containing 30% SSA withstands 125 freeze-thaw cycles, superior to PC. After seawater mixing, SSA performs better in terms of the generation of high-density C-S-H gel. The promoting effect of SSA on the transformation of capillary pores into gel pores in cement paste and its content threshold are amplified. The chemical binding of Cl- and SO42- with amorphous Al2O3 in SSA promotes the conversion of AFt to AFm. Additionally, based on multi-criteria analysis, the seawater-mixed sintered sludge cement is more competitive.