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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。
Steel fiber reinforced concrete has good tensile properties and toughness after cracking, and has been widely used in the repair and reinforcement of engineering structures. For the repaired corroded components, the bond between steel fiber reinforced concrete and corroded steel bars is the key factor that affects the mechanical properties. Firstly, the steel bars were pre-corroded by electrochemical method, then the cleaned pre-corroded steel bars were used to make the drawn test pieces, and then the center pull test was conducted to study the bond performance between the steel bars and the steel fiber reinforced concrete. The experimental results show that the incorporation of steel fiber can change the specimen from cleavage failure to pull-out failure, and the bond strength ratio increases by 4.4% -7.5%. With the decrease of the bond length, the relative slip between the loading end and the free end The average slip corresponding to the peak bond stress gradually increases. The effect of corrosion rate on the bond strength is related to the bond length. When the corrosion rate reaches about 15%, the bond length For the 3d (d is the diameter of the steel bar), the bond strength decreases 21%, while the bond length 7d does not change the bond strength. Based on the test results, empirical formula of bond strength based on corrosion rate and bond length was established. The calculated results agree well with the experimental results.