A novel shearing fracture morphology method to assess the influence of freeze-thaw actions on concrete-granite interface

摘要

In cold regions, the bonding strength of concrete-rock interface is considerably influenced by freeze-thaw (F-T) actions. However, accurate approaches to evaluate the influence of F-T cycles on interfacial strength are relatively few. In this study, a novel shearing fracture morphology method for reflecting the influence of F-T cycles on the bonding performances of concrete-rock interface is proposed. A three-dimensional (3D) laser scanning technology is firstly used to determine the interfacial roughness index and joint roughness coefficient (JRC). Thereafter, interfacial debonding tests after subjecting the samples to different F-T cycles (i.e., 0, 10, 20, 30, and 50) are performed using a slant shear test. Based on the measurements obtained by image processing technology (i.e., binarization and 3D reconstruction image observations), a novel shearing fracture morphology approach is proposed to reflect the interfacial morphology features and their residual concrete adhesion area at different F-T cycles. Moreover, the relationships among F-T cycles, interfacial fracture morphology, and shear strength are discussed. The conclusions drawn are as follows: (i) the interfacial bonding strength depends on the roughness and the cementing force between cement and mineral particles of granite; (ii) F-T cycles have a significant effect on the bonding performance of concrete-granite interface caused by the deterioration effects of cementation; (iii) the proportions of concrete adhesion, fracture morphology, and JRCs have positive correlations. This study provides a new approach for evaluating the influence of F-T actions on concrete-rock interfacial debonding features.