A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Debonding behaviors and micro-mechanism of the interface transition zone in sandstone-concrete interface in response to freeze-thaw conditions
Abstract Comprehensive understanding the micro-debonding behavior and micro-mechanism at the interface transition zone (ITZ) of rock-concrete interfaces is essential for protecting shotcrete in tunnels. The ITZ is a weak area of the rock-concrete interface and is vulnerable to freeze-thaw (F-T) deterioration. Such deterioration can cause tunnel support failure. We used nanoindentation technology, stereo microscopy, and scanning electron microscopy (SEM) and considered several F-T actions to obtain four primary findings: (1) The elastic modulus and hardness values of the ITZ decrease continuously as the number of F-T cycles increases, and the trends of these changes are highly consistent. However, the decline of hardness value exceeds that of the elastic modulus as F-T cycling continues. (2) The thickness of the ITZ has a positive correlation with the number of F-T cycles. For example, the ITZ thickness increases from 60 μm (0 F-T cycles) to 80 μm (20 F-T cycles). (3) The volume fraction of micropores at the interface has a positive linear correlation with the number of F-T cycles; however, the volume fractions of low-density (LD) calcium-silicate-hydrate (C-S-H) gel, high-density (HD) C-S-H gel, and calcium hydrate (CH) at the interface exhibit negative correlations with the number of F-T cycles. These relationships indicate that micropores exert a degradation effect in response to F-T conditions. (4) The ITZ has high porosity and low sensitivity to debonding near the sandstone side. ITZ debonding is induced by F-T cycles because frost expansion and thaw contraction are significantly different in sandstone and cement paste. This study provides a reference for understanding the behavior and mechanism of debonding in rock-concrete interfaces subjected to F-T conditions.
Highlights Nanoindentation technology can evaluate the micromechanical properties of sandstone-concrete binary bodies. Freeze-thaw (F-T) damage can degrade ITZ width. Volume fraction of hydration products quantitatively characterizes the evolution of interfacial microstructure under F-T. A weak zone is identified near the sandstone interface based on changes in micromechanical properties. The uncoordinated deformation of the sandstone-concrete caused ITZ to extend into the fragile sandstone interface.
Debonding behaviors and micro-mechanism of the interface transition zone in sandstone-concrete interface in response to freeze-thaw conditions
Abstract Comprehensive understanding the micro-debonding behavior and micro-mechanism at the interface transition zone (ITZ) of rock-concrete interfaces is essential for protecting shotcrete in tunnels. The ITZ is a weak area of the rock-concrete interface and is vulnerable to freeze-thaw (F-T) deterioration. Such deterioration can cause tunnel support failure. We used nanoindentation technology, stereo microscopy, and scanning electron microscopy (SEM) and considered several F-T actions to obtain four primary findings: (1) The elastic modulus and hardness values of the ITZ decrease continuously as the number of F-T cycles increases, and the trends of these changes are highly consistent. However, the decline of hardness value exceeds that of the elastic modulus as F-T cycling continues. (2) The thickness of the ITZ has a positive correlation with the number of F-T cycles. For example, the ITZ thickness increases from 60 μm (0 F-T cycles) to 80 μm (20 F-T cycles). (3) The volume fraction of micropores at the interface has a positive linear correlation with the number of F-T cycles; however, the volume fractions of low-density (LD) calcium-silicate-hydrate (C-S-H) gel, high-density (HD) C-S-H gel, and calcium hydrate (CH) at the interface exhibit negative correlations with the number of F-T cycles. These relationships indicate that micropores exert a degradation effect in response to F-T conditions. (4) The ITZ has high porosity and low sensitivity to debonding near the sandstone side. ITZ debonding is induced by F-T cycles because frost expansion and thaw contraction are significantly different in sandstone and cement paste. This study provides a reference for understanding the behavior and mechanism of debonding in rock-concrete interfaces subjected to F-T conditions.
Highlights Nanoindentation technology can evaluate the micromechanical properties of sandstone-concrete binary bodies. Freeze-thaw (F-T) damage can degrade ITZ width. Volume fraction of hydration products quantitatively characterizes the evolution of interfacial microstructure under F-T. A weak zone is identified near the sandstone interface based on changes in micromechanical properties. The uncoordinated deformation of the sandstone-concrete caused ITZ to extend into the fragile sandstone interface.
Debonding behaviors and micro-mechanism of the interface transition zone in sandstone-concrete interface in response to freeze-thaw conditions
Pan, Jia (author) / Shen, Yanjun (author) / Yang, Gengshe (author) / Zhang, Huan (author) / Yang, Hongwei (author) / Zhou, Zihan (author)
2021-07-20
Article (Journal)
Electronic Resource
English
Freeze-thaw resistant breathable concrete interface agent
| European Patent Office | 2021
| British Library Online Contents | 2018
| British Library Online Contents | 2018