钢-UHPC组合桥面板湿接缝界面处理方式

针对钢-UHPC （Ultra-high Performance Concrete）组合桥面板湿接缝处混凝土界面人工凿毛困难的问题，提出环氧树脂处理和高压水枪凿毛等新型界面处理方式。为了检验采用涂刷环氧树脂、高压水枪凿除细骨料和高压水枪凿除粗骨料处理后湿接缝的抗裂性能，进行了UHPC湿接缝足尺模型的轴心受拉试验，并与不设湿接缝的桥面板进行试验对比。通过比较不同界面处理后的UHPC名义拉应力-应变曲线及UHPC名义拉应力-裂缝宽度曲线，分析了3种湿接缝的开裂荷载、裂缝分布，揭示了不同界面处理下的接缝受力机理。试验结果表明：3种界面处理方式的湿接缝破坏形式相同，均是首先在新旧混凝土交界面上出现初始裂缝，随着荷载增加裂缝逐渐发展至贯通，UHPC退出工作，最后钢材受拉屈服达到极限状态。界面采用环氧树脂处理、高压水枪凿除细骨料、高压水枪凿除粗骨料的试件开裂荷载分别为不设湿接缝试件的53.7%、92.2%、81.9%，高压水枪界面处理的湿接缝比起环氧树脂处理的湿接缝具有开裂晚、裂缝发展慢的特点，且高压水枪凿除细骨料比高压水枪凿除粗骨料的界面处理方式更优。通过试验证实了新旧混凝土交界面是桥面板的最薄弱位置，且2种高压水枪凿毛的界面处理方式均能够满足实桥荷载作用下桥面板的抗裂强度要求，在施工条件允许的情况下推荐使用高压水枪凿除细骨料的界面处理方式。

Interfacial Treatment Measures of Wet Joints in Composite Bridge Deck Composed of Steel and UHPC Layer

To confront the difficulty in manual roughing of wet joint concrete interfaces in a composite bridge deck composed of steel and a Ultra-High Performance Concrete (UHPC)layer, three new interfacial treatments were proposed:smearing of epoxy resin, high-pressure water blasting of fine aggregate, and high-pressure water blasting of coarse aggregate. The crack resistance characteristics of wet joint interfaces treated by the three measures were examined by conducting tensile tests on full-scale specimens of UHPC wet joints. Further, the test results were compared with that of a deck without wet joints. By comparing the tensile stress-strain curves and the tensile stress-crack width curves of the three interfacial treatments, the cracking loads and crack distributions were analyzed and the force mechanisms were studied. The results show that the failure modes of wet joint interfaces treated by the three interfacial treatments are the same. All the wet joint interfaces developed an initial crack at the junction interface of new and old concrete. The cracks propagated gradually with the increase in test load until they fully penetrated the deck, indicating the failure of UHPC. Finally, the steel yielded in tension and the specimens reached the ultimate limit state. Cracking loads of the three specimens treated by smearing of epoxy resin, roughing of fine aggregate, and roughing of coarse aggregate were 53.7%, 92.2%, and 81.9% of that of the specimen without wet joints, respectively. Wet joint interfaces roughed by high-pressure water developed cracks tardily and gradually when compared to those in the wet joint interfaces treated by smearing the epoxy resin. The mechanical behavior of the wet joint interface treated by roughing of fine aggregate is superior to that treated by roughing of coarse aggregate. It is verified that the junction interface of new and old concrete is the weakest area of the bridge deck. Both the interfacial treatments by high-pressure water roughing meet the crack resistance requirements of bridge decks under actual loads. Among them, the interfacial treatment by roughing of fine aggregate with high-pressure water is the most recommended, provided the construction conditions permit the implementation of this measure.