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对经过0次、25次、50次、75次、100次冻融循环作用后的再生混凝土(粗骨料取代率100%)进行拉拔试验研究,得出不同冻融循环次数、保护层厚度和锚固长度下钢筋与再生混凝土间黏结性能的变化规律。结果表明:随着冻融循环次数的增加,钢筋与再生混凝土间的黏结强度逐渐降低,而滑移值逐渐增加;黏结强度随着相对保护层厚度的增加而增大且呈线性关系,随着相对锚固长度的增加,黏结强度却随之减小,当相对保护层厚度和锚固长度增加到一定值后,黏结强度基本保持不变。基于试验结果给出黏结-滑移曲线,曲线分为微滑移线性阶段、滑移阶段、滑移加速阶段、非线性下降段和残余阶段等5个阶段。通过分析试验数据提出不同影响因素下各阶段黏结锚固特征值的拟合计算公式,为我国冻融环境下再生混凝土结构的耐久性设计提供参考。
Recycled concrete (coarse aggregate substitution rate 100%) after 0, 25, 50, 75 times and 100 cycles of freeze-thaw cycles were tested on the pull-out test, and the number of different freeze-thaw cycles, the thickness of the protective layer And the anchoring length between the reinforcement and recycled concrete bond performance changes. The results show that with the increase of the number of freeze-thaw cycles, the bond strength between rebar and recycled concrete gradually decreases and the slip value increases gradually. The bond strength increases linearly with the increase of relative protective layer thickness, With the increase of anchorage length, the bond strength decreases. When the relative thickness of protective layer and anchorage length increase to a certain value, the bond strength remains basically unchanged. Based on the experimental results, the bond-slip curve is given. The curve is divided into five stages: linear stage, slipping stage, slipping acceleration stage, non-linear descending stage and residual stage. Based on the analysis of the experimental data, the fitting formulas of the bond-anchored eigenvalues of the various stages under different influence factors are put forward to provide references for the design of durability of recycled concrete structures in freezing-thawing environment in China.