Monitoring Corrosion of Steel Bars in Reinforced Concrete Structures

Table 1

Methods for evaluating corrosion in concrete structures [5].

S. no.	Method	Advantages	Limitations	Principle
1	Galvanostatic pulse method	Measures half-cell potential and electrical resistance simultaneously	Unstabilized readings	Based on the polarization of rebar by means of small constant current
2	Linear polarization resistance (LPR)	Rapid and requires only localized damage, more detailed information	Measurements are affected by temperature and humidity	Electrical conductivity of fluid can be related to its corrosiveness
3	Half-cell potential	Simple, portable, results in the form of equipotential contours	Needs preparation, saturation required, not very accurate, and time consuming	Electric potential of rebars is measured relative to half-cell and indicates probability of corrosion
4	Time domain reflectometry (TDR)	More robust, easy, and locates corrosion and identifies extent of damage	Less sensitive	By applying a sensor wire alongside of the reinforcement a transmission line is created. Physical defects of the reinforcement will change the electromagnetic properties of the line
5	Ultrasonic guided waves	Identify location and magnitude of corrosion	Not very reliable	Based on propagation of ultrasonic waves
6	X-ray diffraction and atomic absorption	Simple and reliable	Hazardous	Intensity of X-ray beams reduces while passing through a material