锈蚀对钢筋与钢纤维混凝土黏结性能的影响

Effect of Corrosion on Bond Behavior of Rebar Embedded in Steel Fiber Reinforced Concrete

关键词:  钢纤维混凝土  锈蚀钢筋  中心拉拔  黏结性能  滑移

Key words:  steel fiber reinforced concrete(SFRC)  corroded rebar  central pull out test  bond behavior  slip

摘要:

通过中心拉拔试验,探究了钢筋与钢纤维混凝土（SFRC）间的黏结滑移机理,并以钢筋锈蚀率为参数,研究了氯离子侵蚀作用对钢筋与SFRC黏结性能的影响.结果表明：在达到黏结强度（峰值黏结应力）之前,钢筋自由端滑移较加载端小;在达到黏结强度之后,钢筋自由端与加载端滑移同步变化,黏结应力由钢筋肋间混凝土与周围混凝土之间的咬合力提供.尽管桥接锈胀裂缝的钢纤维遭受了一定程度的锈蚀损伤,但所有锈蚀试件仍然表现为延性的劈裂拔出破坏;随着钢筋锈蚀率的增大,黏结强度先略微增大而后逐渐减小,当钢筋锈蚀率在801%之内时,其黏结强度不低于未锈蚀试件,当钢筋锈蚀率约1511%时,其黏结强度损失约为35%.考虑钢筋锈蚀率的影响,基于Harajli模型得到锈蚀钢筋与SFRC黏结强度的经验公式.

Abstract:

Corrosion of reinforcement and steel fiber in steel fiber reinforced concrete(SFRC) under chloride attack may have a great effect on bond behavior of rebar embedded into SFRC. Bond behavior between rebar and SFRC subjected to accelerated chloride attack through central pull out test, and the local bond mechanism of rebar embedded in SFRC was investigated in the meantime. The experimental results indicate that the slip at the free end of the rebar is lower than that at the loading end prior to the peak bond stress. At the post peak stage, the slip at the free end and loading end develops synchronously, and the bond stress is mainly provided by mechanical interaction between concrete teeth between ribs of rebar and surrounding SFRC. The corroded specimens all failed in combined splitting and pull out tests although steel fibers on the surface and that bridging the corrosion induced cracks suffer a certain degree of corrosion damage. With the increasing corrosion ratio, the bond strength first increases slightly and then decline gradually. The bond strength can be remained when the corrosion ratio is lower than 801%, whereas the bond strength loss is approximately 35% at corrosion level approaching 1511%. Based on Harajli model, a bond strength model considering the effect of rebar corrosion is obtained for predicting the bond strength between corroded rebar and SFRC.