This study focused on the interfacial transition zone (ITZ) between magnesium phosphate cement (MPC) paste and Portland cement paste (PCP). Multi-scale analyses were conducted to explore bonding characteristics and interfacial shear strengths of the ITZ with an innovative composite specimen. Meanwhile, ITZ was investigated by the Nano-indentation test, the scanning electron microscope (SEM), and the energy-dispersive spectrometer (EDS). Based on the damage mechanics and the interface kinematics formula, the viscous behavior and friction behavior were coupled together for the first time to develop the constitutive relation of the interface damage. A finite element (FE) model of MPC-PCP interface shear strength was developed and conducted to validate the proposed constitutive relation of the interface damage. Sensitivity analysis of repair size was predicted by the effect of different sizes on shear strength. The 7d shear strength of the repair interface reached 5.2 MPa, which indicates that MPC has good bonding with PCP. Investigated by SEM/EDS analysis, the cracks appeared at 10 μm away from PCP edge and the width at 6 h and 3d was around 3–5 μm. According to the nano-indentation test, the elastic modulus varied greatly in the ITZ and the lowest value located 10 μm away from the PCP side. Numerical results from FE models were found consistent with the experimental results, which validates the proposed constitutive relation of the interface damage.

这项研究的重点是磷酸镁水泥（MPC）浆和波特兰水泥浆（PCP）之间的界面过渡区（ITZ）。进行了多尺度分析，以探索具有创新复合材料试样的ITZ的粘结特性和界面剪切强度。同时，通过纳米压痕测试，扫描电子显微镜（SEM）和能量色散光谱仪（EDS）研究了ITZ。基于损伤力学和界面运动学公式，将粘滞行为和摩擦行为首次结合在一起，建立了界面损伤的本构关系。建立并进行了MPC-PCP界面抗剪强度的有限元模型，以验证所提出的界面损伤的本构关系。通过不同尺寸对剪切强度的影响来预测修复尺寸的敏感性分析。修复界面的7d剪切强度达到5.2 MPa，表明MPC与PCP具有良好的粘结性。通过SEM / EDS分析研究发现，裂纹在距PCP边缘10μm处出现，在6 h和3d处的宽度约为3-5μm。根据纳米压痕测试，其弹性模量在ITZ中变化很大，并且最低值位于距PCP侧10μm处。有限元模型的数值结果与实验结果吻合，验证了所提出的界面损伤的本构关系。通过SEM / EDS分析研究发现，裂纹在距PCP边缘10μm处出现，在6 h和3d处的宽度约为3-5μm。根据纳米压痕测试，其弹性模量在ITZ中变化很大，并且最低值位于距PCP侧10μm处。有限元模型的数值结果与实验结果吻合，验证了所提出的界面损伤的本构关系。通过SEM / EDS分析研究发现，裂纹在距PCP边缘10μm处出现，在6 h和3d处的宽度约为3-5μm。根据纳米压痕测试，其弹性模量在ITZ中变化很大，并且最低值位于距PCP侧10μm处。有限元模型的数值结果与实验结果吻合，验证了所提出的界面损伤的本构关系。