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为了分析冻融环境对钢筋与混凝土间粘结界面显微结构的影响,利用扫描电镜对取自冻融作用前后钢筋周围不同位置处的界面样品进行了观察,并通过宏观力学试验验证了粘结性能随冻融作用的退化规律。研究结果表明:冻融作用对粘结界面的显微结构和力学性能有很大影响,且影响效果与界面相对于钢筋位置有关。原本较为致密的钢筋顶部界面区内出现了细小的冻胀裂纹,而比较酥松的钢筋底部界面区内进一步生长出取向程度更高的凝胶体。粘结界面显微结构的变化导致钢筋混凝土间宏观粘结性能不断退化,具体体现于粘结强度不断损失和粘结破坏形式的劣化。
In order to analyze the influence of freeze-thaw environment on the microstructure of the bond interface between steel bar and concrete, the interfacial samples taken from different locations around the steel bar before and after freeze-thaw were observed by scanning electron microscopy and the bond was verified by macroscopic mechanical tests Performance degradation with the law of freezing and thawing. The results show that the freeze-thaw effect greatly affects the microstructure and mechanical properties of the bonded interface, and the effect is related to the position of the interface relative to the rebar. The original denser steel top interface area appeared small frost heave cracks, while the more crisp steel bottom interface area to further grow a more oriented gel. The change of the microstructure of the bonded interface leads to the continuous deterioration of the macroscopic bond between the reinforced concrete, which is manifested in the continuous loss of bond strength and the deterioration of the form of bond failure.