Mechanical Properties and Water Resistance of Magnesium Oxychloride Cement–Solidified Residual Sludge

As a solid waste, the amount of residual sludge produced by municipal wastewater treatment process is escalating. How to dispose it properly attracting much attention in society. Herein, solidifying using magnesium oxychloride cement (MOC) promising for converting into building materials. Various factors mass ratio (RW/S) liquid solid, molar (Rn) MgO MgCl2 MOC, (Rm) concentration Na2SiO3 (DNa2SiO3), and dosage fly ash (DF) influenced unconfined compression strength (RC) as–obtained MOC–solidified sludge, was characterized SEM XRD analysis. The results show that value RC MOC–residual solidified blocks increased initially then decreased as Rn Rm increased, respectively, 60–day curing. At 10–day curing, equilibrium reached at all RW/S values except 1.38, with increasing. maximum 60 days 20.90 MPa obtained = 0.90, 5.0, 1.00. Furthermore, adding or could improve RC. water resistance test showed SM13 NF5 samples exhibited good alkaline after immersion 7 14 an aqueous solution pH 7.0–11.0. increase duration solutions. also help neutral basic This work provides important theoretical basis possibility efficient disposal comprehensive utilization through solidification/stabilization technology MOC from perspective mechanics resistance.