桥梁混凝土结构接缝的耐久性能

目前桥梁混凝土结构的耐久性研究主要集中于整体成型的混凝土部分，而没有考虑接缝的影响。为探明混凝土接缝的耐久性能，对分段成型的桥梁混凝土结构中常用的直接湿接缝、凿毛湿接缝、干接缝和环氧胶接缝等四类接缝进行氯离子侵入、碳化、冻融及接缝部位钢筋锈蚀等耐久性试验结果开展分析。结果明确表明：不同类型接缝的耐久性能虽有差别，但都是混凝土抗环境作用的薄弱部位，其中，通过机械凿毛改善新老混凝土结合的措施可能会对接缝连接界面造成损伤，损害结构的耐久性能；干接缝的各项耐久性指标均明显劣于其余类型接缝，不应用在环境不良的地区；环氧胶接缝并未表现出明显优于其余类型接缝的耐久性能，仍需进一步进行相关研究；接缝部位的钢筋包括不锈钢筋在内都反映出更严重的腐蚀状况。接缝是混凝土耐久性最关键的部位，连接界面上的水泥砂浆基体或施工损伤等因素是其抗环境作用性能下降的主要因素，因此混凝土的耐久性研究应更多关注其接缝，设计、施工及维护都应有相应的措施。

Study on durability of joints in concrete bridge structures

Existing durability studies on concrete bridge structures mainly focus on monolithic concrete without considering the effect of joints. Experimental research was carried out to investigate the durability of joints commonly used in concrete bridges, including the direct wet joints, roughened wet joints, dry joints and epoxied joints. By subjecting the joints to chloride ion penetration, carbonation, frost, and reinforcement corrosion, some conclusions are obtained. All types of joints are the most weak positions of concrete, although their durability is different from each other. Although, the new-old concrete interface can be densified by mechanical roughening, initial damage on the interface will emerge, and the durability of concrete will be damaged. Dry joints should not be used in severe environments since their durability indicators are obviously inferior to those of other joints. The durability of epoxied joints is not as satisfied as expected, so  further research should be conducted. Reinforcements, including strainless steel reinforcements, at joints can effectively reflect more severe corrosion than monolithic concrete. The cement layer on the interface or the construction damage is responsible for the degradation of the resistance of joints to environments. Therefore, the durability research of concrete should be paid more attention to the joints, and relevant measures should be developed at the stages of design, construction, and maintenance.