ASSESSMENT OF DATA FROM 3 ELECTROCHEMICAL INSTRUMENTS FOR EVALUATION OF REINFORCEMENT CORROSION RATES IN CONCRETE BRIDGE COMPONENTS

Data from three prototype instruments on the reinforcement corrosion rates of concrete bridge components were evaluated for accuracy and consistency. Two instruments applied the linear polarization technique, one with and one without current confinement, and the third used superimposed current pulses of high and low frequencies with current confinement. Repeatability of the measurements was expressed by standard error of the mean (EM) and was found to be almost the same for all three instruments. Systematic error (bias) was estimated by comparing data obtained by the instruments in the field and in laboratory tests, A good correlation was shown between results from the different instruments, demonstrating that all three instruments provided data relevant to the true corrosion rate in concrete structures. The effect of guard electrodes (GE) on the measured values of the corrosion rate was illustrated for the device using superimposed current pulses.