Study On Corrosion Rate Of Reinforcement In Conductive Fiber Reinforced Concrete Under Chloride Corrosion

Concrete has self-weight,low tensile strength and easy cracking and other shortcomings,in order to make up for these defects,fiber materials incorporated into concrete to improve the performance of concrete has become a research hotspot,common fiber materials are mainly carbon fiber,carbon nanotubes and steel fibers,etc.,these fiber materials have a common feature is that they have good conductivity,but at present,the incorporation of conductive fiber materials for reinforced concrete steel corrosion has not been clearly determined.Firstly,the mechanical properties of different fiber types of concrete were studied,the content of carbon nanotubes was 0.08%,0.1% and 0.12%,the content of carbon fiber was 1%,1.2% and 1.4%,and the content of steel fiber was 0.6%,0.8% and 1.0%,and the fiber concrete with different fiber types and different dosages was studied,and it was found that the incorporation of fibers could improve the splitting tensile strength and compressive strength of concrete.The main reason is that the fiber limits the formation of microcracks inside the concrete and limits its lateral deformation;The resistance of different fiber content concrete was measured,and it was found that for the same kind of fiber concrete,with the increase of fiber content,the resistance of concrete will gradually decrease,mainly considering that the conductive mode inside the concrete has changed,from ionic conductivity to ionic conductivity,tunnel effect and contact conductivity work together,and with the gradual increase of fiber content,a better conductive network will be formed inside concrete;Comparing fibers between different fiber types,under the same dosage,carbon nanotubes have the best effect on reducing the resistance of concrete,and the worst effect on steel fibers,mainly because the diameter of carbon nanotubes is small,the length-diameter ratio and specific surface area are large,and the direct contact resistance of fibers is smaller.Using electrochemical workstation to measure the reinforced concrete test block under natural immersion,electrochemical indicators mainly include polarization curve,corrosion potential,corrosion current density,polarization resistance and corrosion rate,for the same kind of fiber,with the increase of fiber content,corrosion current density increases,corrosion potential decreases,from the polarization curve,the curve moves more in the direction of negative potential and corrosion current increase;For different fiber types,from the perspective of electrochemical parameters,the corrosion rate of steel fiber concrete embedded steel bar is the fastest,followed by carbon fiber,and carbon nanotubes are the smallest,which considers the joint effect of concrete resistance and internal porosity of concrete.Finally,by breaking the reinforced concrete,it is found that with the gradual increase of fiber content,the weight loss rate of embedded steel bars gradually increases,and the strength loss rate also gradually increases,but the strength loss rate is greater than the weight loss rate,which is mainly because the corrosion of steel bars is nonuniform rust,which will cause stress concentration caused by erosion pits,so the strength loss rate has an amplifying effect on the weight loss rate;Comparing the rust characteristics of the three fiber types of concrete,it is found that with the decrease of the resistance in the concrete,the number of pits on the surface of the steel bar will gradually increase,and compared with the embedded steel bars of carbon fiber and carbon nanotube concrete,the pits embedded with steel fiber concrete will show a clustered distribution and the pit area is larger.The thesis has 47 figures,24 tables,and 69 references.