Study on Evaluation of Bond Performance of Concrete and Improvement

在本研究中，除了传统的弯曲粘结强度之外，我们还使用拉伸软化图来评估混凝土的粘结性能，并改善了粘结性能。研究了剪切力和拉力下接头的粘合性能。通过有限元分析，结合拉伸软化图，对混凝土结构修补材料的断裂行为进行了分析。采用喷丸法、水射流法和含缓凝剂的纸片冲洗法对混凝土接缝表面进行粗糙化处理。通过使用功率谱、分形维数和总表面积来量化接合表面的粗糙度。通过弯曲粘合强度、断裂能和拉伸软化图的形状来评价接头的粘合性能。经过这些参数的比较，得出拉伸软化图是有效的。通过实验和数值分析研究了尺寸对混凝土弯曲粘结强度的影响。结果发现，当接缝处粘结性能较差时，尺寸效应显着。对混凝土结构修补材料的收缩和开裂行为进行了研究。对修复材料的开裂和因收缩引起的界面分层进行了数值分析，结果与实验结果一致。界面张力软化图数值分析的有效性得到了证实。指出垂直接合面（修补材料端面）的表面处理很重要，因为处理对修补材料的收缩和开裂行为影响很大。

In this study, we evaluated bond performance of concrete by using the tension softening diagrams in addition to the conventional flexural bond strength and improved the bond performance. The bond performance of joints under shear force as well as under tension forces was investigated. The fracture behavior of repair materials for concrete structures was analyzed through FEM with the tension softening diagrams.The concrete joint surfaces were roughened by means of a shot blast method, a water jet method and a wash out method with a paper sheet containing retarder. The roughness of the joint surfaces was quantified by using the power spectrum, the fractal dimension and the- total surface area. The bond performance of joints was evaluated through the flexural bond strength, the fracture energy and the shape of the tension softening diagrams. After the comparison of these parameters, it was concluded that the tension softening diagrams were efficient.The size effect on the flexural bond strength of concrete was investigated through experiments and numerical analysis. It was found that the size effect was remarkable when the bond performance at joints was poor.he shrinking and cracking behavior of repair materials for concrete structures was investigated. The cracking in repair materials and the delamination on the interfaces due to the shrinking were numerically analyzed and the results coincided with the experimental ones. The efficiency of the numerical analysis with tension softening diagrams at interfaces was confirmed. It was pointed out that the surface treatment at vertical joint surface (end surface of repair materials) was important because the treatment gave a large influence on the shrinking and cracking behavior of the repair materials.