Study On The Corrosion Monitoring Of Steel Rebars Based On Piezoelectric Sensing Technique

Rreinforced concrete structures have been widely used in civil engineering.With the increase of their service life,corrosion of steel reinforcements occurs slowly in the natural environment and occurs frequently in hydraulic structures,bridges,as well as roads,among others,which has caused great damage to the safety of the structure.In the current literature,physical and electrochemical methods are two main approaches to detect the corrosion of steel rebars.X-ray diffraction method is not suitable for in-field monitoring owing to their radiation hazard and high cost.In this paper,piezoelectric technology is applied to the corrosion monitoring of steel rebars.Piezoceramics have many advantages,such as the direct piezoelectric effect and the converse piezoelectric effect,wide frequency response range,low cost,quick response and so on.The specific research work includes the following:(1)The monitoring corrosion of steel rebar is experimentally studied by piezoelectric technology and time reversal method.Research work consists of two parts: 1)Corrosion monitoring of steel rebars: in experiment,the piezoelectric transducers was attached to the two ends of the steel bar,and with sodium chloride solution,DC power supply and copper bar constitute the accelerated corrosion system.To ensure that the piezoceramic transducers work properly without corrosion,it was necessary to experimentally study the property of piezoceramic transducers.Secondly,the corrosion monitoring of steel bars is studied,the steel bars under different corrosion state are actively monitored by monitoring system.The relationship between the corrosion rate of steel bar and the peak value of the received signal is established.2)Corrosion monitoring of reinforced concrete: in experiment,the reinforced concrete short columns were produced and piezoelectric smart aggregate and piezoelectric transducers to form a joint monitoring system to identify the corrosion of steel bar.The relationship between the corrosion rate of steel bar and the peak value of the received signal is established and the feasibility of this method has been proved.(2)Research on corrosion monitoring of steel bar based on finite element analysis software.Based on the ABAQUS software,the steel bar model with different section damage depth(35)R can be established.According to the damage depth of the section,the loss rate of the section can be obtained.The correlation between the peak value of the signal and the loss rate of the cross section is verified.(3)Study on the locating corrosion of steel bar based on piezoelectric technology.In this paper,the corrosion localization of steel bars is described from the aspects of simulation and experiment: 1)Based on ABAQUS,the corrosion location is determined by the velocity of guided wave propagation in steel bar and the time difference between the first wave and the defect echo in the received signal;2)In practice,the propagation of the guided wave has a multimodal state,the signal with the lower mode is selected and the signal is obtained by the steel bar with defects.The influence of the interference signal in the signal is reduced by the wavelet decomposition method,and the corrosion location of the steel bar is further determined.