An experimental study was conducted to investigate the effects of stirrup corrosion, concrete strength and casting position on the behaviour of the bond between steel bars and concrete. Accelerated corrosion was applied to corrode the stirrups in concrete specimens under laboratory conditions. In total, 180 specimens were cast and tested in this experiment. The specimens had three nominal concrete strengths of C20, C40 and C50 with two deformed steel bars of 18 mm in diameter set in a 200 × 200 mm diagonal concrete prism with two stirrups of 8 mm in diameter to provide confinement. The steel bars were cast with different pouring positions, namely the upper and lower ends. Five corrosion levels were investigated, namely 0, 5, 10, 15 and 20%; 12 specimens were investigated for each corrosion level. A pull-out test was carried out to obtain the bond–slip curves. The test results indicate that the porosity of concrete has a great effect on bond degradation with the increase of the steel corrosion level.

中文翻译：

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受腐蚀箍筋约束的钢筋和混凝土的粘结退化：混凝土等级和浇注位置的影响

进行了一项试验研究，研究了箍筋腐蚀、混凝土强度和浇注位置对钢筋与混凝土之间结合性能的影响。在实验室条件下采用加速腐蚀腐蚀混凝土试件中的箍筋。在本实验中，总共铸造和测试了 180 个试样。试样具有 C20、C40 和 C50 三种标称混凝土强度，两个直径为 18 mm 的变形钢筋设置在 200 × 200 mm 对角混凝土棱柱中，两个箍筋直径为 8 mm，以提供限制。钢筋以不同的浇注位置浇注，即上端和下端。考察了五个腐蚀等级，即0、5、10、15和20%；对每个腐蚀等级研究了 12 个试样。进行拉拔试验以获得粘合-滑移曲线。试验结果表明，随着钢筋腐蚀程度的增加，混凝土的孔隙率对粘结退化的影响很大。