锈蚀钢筋与钢纤维混凝土的黏结性能试验研究

钢纤维混凝土具有良好的开裂后拉伸性能和韧性，已被广泛用于工程结构的修复加固中。对于所修复的锈蚀构件，钢纤维混凝土与锈蚀钢筋的黏结性能是影响其力学性能的关键因素。首先通过电化学方法对钢筋进行预锈蚀，进而采用清理干净的预锈蚀钢筋制作拉拔试件，然后通过中心拉拔试验研究锈蚀钢筋与钢纤维混凝土的黏结性能。试验结果表明：钢纤维的掺入能够使试件从劈裂破坏转变为拔出破坏，同时黏结强度比提高4.4%~7.5%；随着黏结长度的减小，加载端与自由端的相对滑移也逐渐减小，而峰值黏结应力对应的平均滑移却逐渐增大；锈蚀率对黏结强度的影响与黏结长度相关，与未锈蚀试件相比，当锈蚀率达到约15%时，黏结长度为3d（d为钢筋直径）试件的黏结强度减小21%，而黏结长度为7d试件的黏结强度基本不变。基于试验结果，建立了以锈蚀率和黏结长度为参数的黏结强度经验公式，计算结果与试验结果吻合较好。

Experimental study on bond behavior between corroded rebar and steel fiber reinforced concrete

Steel fiber reinforced concrete (SFRC) has been used in retrofitting and strengthening of engineering structures extensively, depending on fine tension properties after cracking and toughness. In the case of corroded members repaired using SFRC, the bond behavior between corroded rebar and SFRC is a key factor for the mechanical properties of repaired members. In the present study, an electrolyte corrosion technique was firstly used to accelerate steel rebar corrosion, and then the corroded rebar was cleaned up and used for pullout specimens, and finally the bond behavior of corroded rebar and SFRC was studied through central pull-out test. The experimental results indicate that the addition of steel fiber can transform the splitting failure to pullout failure mode, and the bond strength ratio increases by 4.4%-7.5%. With the decrease in bond length, the relative slip between loading and free ends decreases whereas the average slip at the peak bond stress increases. The influence of corrosion ratio on the bond strength of reinforcement and SFRC is related to the bond length. When the corrosion ratio increases to about 15%, the bond strength decreases by 21% for specimens with bond length 3d (d is diameter of reinforced rabar), while the bond strength almost remains a constant for specimens with bond length 7d. Based on the experimental results, an empirical equation, considering corrosion ratio and bond length, is proposed for predicting the bond strength, and the calculated result agrees well with the tested value.