Abstract: To promote the resource utilization of engineering waste soil (EWS) and enhance the comprehensive performance of magnesium oxychloride cement (MOC), the effects of EWS incorporation (0, 20%, 40%, 60%), moisture content (0, 10%, 20%, 30%), and carbonation curing on the flexural strength, compressive strength, and water resistance of MOC were investigated. Experimental results demonstrated that the incorporation of 20% EWS achieved optimal mechanical properties and water resistance of MOC, with a 28 d compressive strength increase of 2.34% and the softening coefficient improvement of 3.8%. When the incorporation amount was elevated to 40%, the compressive strength exhibited only a marginal decrease (0.88%), but the utilization rate of engineering waste soil was significantly improved. Moisture content exerted a notable adverse effect on mechanical performance. Specimens with 30% moisture content showed an 11.6% reduction in compressive strength compared to dried samples, attributed to particle agglomeration induced by water molecules. Carbonation curing enhanced compressive strength by 11.71%-16.54% through pore-filling effects via magnesium carbonate flocs. Furthermore, the synergistic interaction between waste soil incorporation and carbonation curing substantially improved water resistance, yielding a softening coefficient of 0.88 (11.4% increase compared to uncarbonized group) for 20% waste soil-incorporated specimens after carbonation. The results of this study can provide important data support for the application of magnesium oxychloride cement materials in solid waste resource utilization and low-carbon environmental protection.

Key words: engineering waste soil, magnesium oxychloride cement, water resistance, mechanical strength, carbonation curing