Study on the failure mechanism between polyurethane grouting material and concrete considering the effect of moisture by digital image correlation

Abstract

The bond resistance between polyurethane (PU) grouting material and concrete consists of adhesion, friction, and mechanical interlocking and is crucial to the repaired concrete structures. During the repair of the leakage and subsidence of underground concrete pipelines by PU grouting material, the chemical adhesion between PU and concrete interfaces may be influenced by moisture caused by the pipeline leakage and groundwater. In this paper, shear tests and the digital imaging correlation (DIC) method were used to study the effect of moisture on the shear bond performance and failure process of the PU-concrete interface before and after grouting PU with different densities. The results reveal that the differences in bond strength, shear strain and horizontal displacement between the interfaces are significantly reduced with the polymer density, especially for moistened interfaces before grouting and testing. Finally, a finite element model was employed to simulate the bond strength between PU and concrete and validated based on the test results.