Han Xiangyu, Zhao Qilong, Jia Bin, Liu Jinqiao, Li Qionglin, Zhang Quan
School of Civil Engineering and Architecture, Southwest University of Science and Technology, Mianyang 621010, China.
China Railway Construction Kunlun Metro Investment and Construction Management Co., Ltd., Chengdu 610031, China.
Materials (Basel). 2025 Jan 3;18(1):171. doi: 10.3390/ma18010171.
Defects can be introduced into shotcrete materials after a few freeze-thaw cycles, which has a significant influence on the fracture performance of shotcrete. In this study, a series of shotcrete specimens with varying sizes, geometries, and initial crack lengths were prepared to investigate the fracture properties of notched shotcrete under freeze-thaw conditions. Considering the effects of specimen boundaries and material microstructure, a linear closed-form solution was proposed to determine the fracture toughness of frost-damaged shotcrete. The fracture toughness was found to be a reliable material constant, independent of specimen geometry variations. Results from three-point bending (3PB) tests show that freeze-thaw cycles severely weaken the fracture toughness of shotcrete, which is consistent with CT scan images of the damaged microstructure of the shotcrete specimens. Moreover, specimens with longer initial notches exhibited more severe freeze-thaw damage, which should be carefully considered in practical engineering assessments. These findings highlight the critical importance of considering freeze-thaw effects and notch length when evaluating the durability of shotcrete in cold region applications.
经过几次冻融循环后，喷射混凝土材料中会出现缺陷，这对喷射混凝土的断裂性能有重大影响。在本研究中，制备了一系列尺寸、几何形状和初始裂纹长度各不相同的喷射混凝土试件，以研究冻融条件下带缺口喷射混凝土的断裂特性。考虑到试件边界和材料微观结构的影响，提出了一种线性封闭解来确定冻融损伤喷射混凝土的断裂韧性。发现断裂韧性是一个可靠的材料常数，与试件几何形状变化无关。三点弯曲（3PB）试验结果表明，冻融循环严重削弱了喷射混凝土的断裂韧性，这与喷射混凝土试件受损微观结构的CT扫描图像一致。此外，初始缺口较长的试件表现出更严重的冻融损伤，在实际工程评估中应仔细考虑这一点。这些发现凸显了在评估寒冷地区应用中喷射混凝土耐久性时考虑冻融效应和缺口长度的至关重要性。
