Bond Behavior Between The Magnetized Rebar And Steel Fiber Reinforced Concrete

The bond between steel rebar and concrete is the basic element ensuring the proper functioning of the reinforced concrete structures.The adding of steel fibers into concrete can improve the bond performance between rebar and concrete,but too many steel fibers can damage the fluidity of concrete,which,instead,influence the steel-concrete bonding.This contradiction is particularly obvious for the wet joints of the prefabricated construction,where,not only the operation space is limited,concrete is difficult to be vibrated and fully compacted,but also a high steel-concrete bonding is required.On this basis,a new method utilizing the magnetized rebar to enhance the steel-concrete bonding is proposed in this paper.This method requires less steel fibers to improve the bond performance.In this way,the steel-concrete bonding can be improved and the fluidity of concrete can also be boosted,which is very suitable for the narrow operation space of construction.This method is clearly introduced in this paper,and a series of experiments were conducted to validate this method.Based on that,the characterization of the slip-bond behavior was investigated and a numerical simulation of the bond-slip between rebar and steel fiber reinforced concrete was established.The detailed content is as follows.(1)The attraction of magnetized rebar to steel fibers can effectively gather the steel fibers around rebar forming a strong core steel-concrete bonding area for which the bonding performance and the cracking resistance is very high.The benefit is not only bond strength is improved but also the fluidity of concrete.The effective steel-concrete bonding of the narrow joints can be,therefore,ensured.(2)41 groups of steel-concrete pull-out experiment and its corresponding basic mechanical experiment and the magnetization experiment of steel rebar was performed.The effect of the magnetization strength of rebar,the steel fiber volume fraction and the concrete compacting methods on the steel-concrete bond performance is discussed.(3)Based on the characteristics of concrete cracking and damage,a steel-concrete bond-slip characterization method is proposed and discussed,this method utilizes the common phenomenon of fraction theory to characterize the bonding deterioration due to the fractured damage of surrounding concrete during the pull-out of rebar.(4)The mechanism of steel fibers in SFRC is investigated,and the effect steel fibers,the preferential distribution of steel fibers as well as the effective distribution of steel fibers are also discussed according to the casting conditions of concrete and the mechanism of steel fibers.The distribution model of steel fibers in simulation is therefore established.A numerical model of steel-concrete bonding is developed based on the steel-concrete bond-slip characterization method and the distribution model of steel fibers.