Loading rate-dependent mechanical properties and crack evolution characteristics of MOC-waste soil composite material

• A new MOC-waste soil composite was developed to recycle solid waste. • Crack evolution characteristics during material failure process were uncovered. • Regulation mechanism of loading rate affecting material failure was revealed. • This new composite material boosts its strength and durability. To effectively utilize construction waste soil generated from urban engineering projects, it was combined with magnesium oxychloride cement (MOC) to develop a new, environmentally friendly composite material. To enhance its impact resistance and dynamic performance, particularly tensile strength and crack propagation, split Hopkinson pressure bar and Brazilian disc experiments were conducted. The digital image correlation method was used to analyze the dynamic tensile behavior and damage evolution of the composite at various loading rates. Results show that the MOC composite demonstrates a clear loading-rate dependence during dynamic loading, with its tensile strength increasing as the loading rate rose. The failure pattern shifts from tension-dominated to mixed, and eventually to shear-controlled, with cracks primarily initiating and propagating from the center or contact edges of the specimens. The addition of construction waste soil fills internal pores within the cement matrix, promoting densification and resulting in improved mechanical strength and toughness of the composite. The crack network becomes more intricate with higher loading rate, suggesting that crack propagation follows more complex evolutionary patterns under dynamic conditions. The agreement between simulation results and experimental data provides theoretical support for understanding the mechanical response and damage evolution of the MOC composite material.