A novel insight into the interface fracture between magnesium phosphate cement mortar and cement concrete

Abstract

ABSTRACT This paper focused on fracture problem about interfacial transition zone (ITZ) formed after repairing between magnesium phosphate cement (MPC) mortar and old Portland cement concrete (PCC) pavements. Firstly, the mode Ⅱ cracks on the ITZ were hypothesized and the interface fracture model with dislocation theory was proposed. The stress field at the crack tip was represented by Airy stress potential function and Fourier Transform, and the structural characteristics of the kernel solution of Cauchy were retained. Then, combined with the oscillation term, the Dirac function was replaced by the normal distribution function to obtain stable fracture parameters. Besides, the ϵ about 8 ‰ of the crack length in model was analyzed. Secondly, the elastic moduli of ITZs were obtained by nanoindentation experiments. Results showed the elastic modulus of ITZ between MPC mortar and ITZ-1 (the interface in concrete) was lowest. Such weakest position in repair interface was further verified by finite element analysis (FEA). Finally, a twodimensional model was developed to validate the fracture model. Simulation results were found consistent with the theoretical solution of interface fracture model. The developed interface fracture model can provide insights for evaluating the shear behavior of the interface between MPC mortar and concrete.