Engineered Cementitious Composites (ECCs) can be used as repair and reinforcement materials, which can improve the shear performance of the structure. Hence, doubled-notched and unnotched half-symmetric loading tests are used to study the mode II fracture properties of ECC and concrete, and the fracture failure morphology and fracture parameters of ECC and concrete are compared. The effects of the notch depth ratios of 0, 0.1, 0.3, and 0.5 and the specimen widths of 200 mm, 250 mm, and 300 mm on the mode II fracture properties of ECC and concrete are investigated. The mode II crack development of ECC can be divided into four stages: microcrack development stage, multiple cracking stage, main crack formation stage, and crack instability development stage. It can be found that ECC not only has high ultimate tensile strain and energy dissipation capacities, but also has obviously better ability to resist the unstable propagation of shear cracks than concrete. ECC can meet the high shear resistance requirements of some parts of the structure.

工程水泥基复合材料 (ECC) 可用作修复和加固材料，可提高结构的抗剪性能。为此，采用双缺口和无缺口半对称加载试验研究了ECC和混凝土的II型断裂特性，并对ECC和混凝土的断裂破坏形貌和断裂参数进行了比较。研究了缺口深度比 0、0.1、0.3 和 0.5 以及试样宽度 200 mm、250 mm 和 300 mm 对 ECC 和混凝土 II 型断裂特性的影响。ECC的II型裂纹发展可分为四个阶段：微裂纹发展阶段、多重开裂阶段、主要裂纹形成阶段和裂纹失稳发展阶段。可以发现，ECC不仅具有较高的极限拉应变和耗能能力，而且抵抗剪切裂缝不稳定扩展的能力明显优于混凝土。ECC可以满足结构某些部位的高抗剪要求。