Quantitative characterization of crumb rubber concrete interfacial transition zone based on microscopic test method

The characteristics of the interfacial transition zone (ITZ) in crumb rubber concrete (CRC) are closely related to its mechanical properties. Selecting appropriate characterization methods for the quantitative analysis of the ITZ’s characteristics is of significant importance for research concerning interfacial strength and crack initiation at the interface. This study employs statistical nanoindentation (NI) combined with the AFM-QNM method to quantitatively characterize the ITZ of CRC. Furthermore, through SEM-EDS observation of the ITZ’s micromorphology and chemical composition analysis, the following conclusions can be drawn: The thickness of the rubber-cement mortar ITZ is approximately 100 μm. The elastic modulus within the ITZ ranges from 20 to 40 GPa, and its hardness ranges from 1 to 3 GPa. The DMT Young’s modulus at the rubber particle-cement mortar interface decreased by 49.8 %, and the interfacial bonding strength decreased by 17.5 %. A distinct microcrack zone exists at the interface between rubber particle and cement paste, accompanied by relatively loose hydration products and a higher distribution of pores.