Systematic study of bonding behavior at the aggregate-mortar interface: Analysis based on experimental and numerical models

Abstract

The bond behavior at the aggregate-mortar interface plays a crucial role in determining the mechanical properties and durability of concrete, especially under environmental stressors such as freeze–thaw cycles and abrasion. This study simulates the bond performance of aggregates in concrete by analyzing the bonding behavior between steel semi-ellipsoidal aggregate and mortar, aiming to explore the different contributions and influencing factors of tensile and shear bond forces at the interface. Using a combination of numerical simulation, theoretical analysis, and model test, the research investigates the variation of interface bond strength at different curing ages and assesses the applicability of the traction-separation law and bilinear cohesive zone model for describing steel aggregate bonding behavior in concrete. The research results demonstrate that the contributions of tensile and shear bond strengths to the bonding behavior are influenced by the geometric shape of the aggregate and the interface conditions. As the aggregate aspect ratio (a/c) increases from 0.4 to 2.2, the simulated stiffness values rise from 46.76kN/mm to 82.19kN/mm, the pull-out force initially decreases and then increases, and the displacement at the point of maximum pull-out force reduces from 0.075 mm to 0.015 mm. This study provides a new perspective for analyzing the mechanical behavior of the concrete interface transition zone and offers insights for related research areas such as freeze–thaw and abrasion resistance.