Evaluation of Corrosion Detection Methods in Reinforced Concrete Structures

Abstract

The objective of this thesis is to conduct a comprehensive comparative analysis of corrosion rate as determined by non-destructive field-applicable techniques and corrosion rate as determined by destructive gravimetric testing as per ASTM G-1. This is accomplished by a two-part experimental program: (1) a laboratory study that monitors the corrosion of reinforcement in reinforced concrete slabs subjected to an accelerated deterioration in a controlled environment, and (2) a field study based on the condition assessment of the deck of the North Channel Bridge, an existing reinforced concrete structure located in Cornwall, ON. Non-destructive techniques analyzed include half-cell potential, linear polarization resistance, galvanostatic pulse technique, connectionless electronic pulse response analysis and four-point electrical resistivity. Generally, corrosion rate as determined by NDT measurements is in agreement, to the same order of magnitude, with the average corrosion rate determined by destructive means. Measurements using the galvanostatic pulse technique are in better agreement with gravimetric measurements than those obtained from the connectionless electronic pulse response analysis and linear polarization technique. Electrical resistivity measurements proved to be a reliable indicator of the concrete condition; these are in agreement with values reported in the literature. From the results of this research, it is concluded that the industry practice of using half-cell potential measurements in the field should be complemented with other NDT techniques, such as electrical resistivity or connectionless electronic pulse response analysis, to obtain a more accurate assessment of the corrosion activity in a reinforced concrete structure undergoing reinforcement corrosion.