Multilayer Microstructure Characterization of the Interfacial Transition Zone between Polymer-Modified Magnesium Phosphate Cement and Portland Cement

Magnesium phosphate cement (MPC) as a fast-setting material has been widely used in the rapid repair of cement concrete pavement. A decisive role was played in the bonding performance of the repair interface between MPC and portland cement concrete (PCC) except for the high early strength and good durability of MPC. Premising the MPC as the rapid repair material for PCC, the characterization and analysis of the interface performance are studied. The data of elastic modulus for the interfacial transition zone (ITZ) is measured by nanoindentation technology while the mechanical properties firstly. The heterogeneity and stratification in the ITZ were characterized by the combination of Raman spectroscopy and nanoindentation test. The content of each material composition was explored with scanning electron microscopy (SEM) and energy-dispersive spectrometer (EDS) experiment and X-ray diffraction (XRD) analysis. Additionally, the adhesion-like substances in the cracks, observed by SEM images in the ITZ, inferred a certain self-healing ability of the polymer-modified magnesium phosphate cement (PMPC). Finally, the elastic modulus of ITZ was simulated by DIGIMAT version 2019.1 software, indicating that the single-layer microstructure analysis is feasible for obtaining elastic modulus of the ITZ without hydration stratification, while the multilayer microstructure analysis is necessary for obtaining elastic modulus of the ITZ with the hydration stratification.

Automated summary

This study characterizes and analyzes the interface performance between magnesium phosphate cement (MPC) and portland cement concrete (PCC), which is used as a fast-setting material for rapid repair. The elastic modulus of the interfacial transition zone (ITZ) is measured using nanoindentation technology, and the heterogeneity and stratification in the ITZ are characterized using Raman spectroscopy and nanoindentation test. The content of each material composition is explored using scanning electron microscopy (SEM) and energy-dispersive spectrometer (EDS) experiment. The study also reveals the presence of adhesion-like substances in the cracks, indicating a certain self-healing ability of the polymer-modified magnesium phosphate cement (PMPC). The simulation results suggest that different microstructure analysis methods are needed depending on the hydration stratification of the ITZ.