APPLICATIONS OF A RAPID NON-DESTRUCTIVE TECHNIQUE IN ASSESSMENT OF CORROSION CONDITIONS OF STEEL IN REINFORCED CONCRETE STRUCTURES

摘要

This paper presents some applications of a rapid technique for non-destructiveassessment of corrosion conditions of steel in reinforced concrete structures. The techniqueinvolves a short time galvanostatic pulse measurement followed with the numerical calculation for correcting the preset polarisation current from the measured ohmic and polarisedpotential responses,so as to be able to estimate the "true" values of ohmic and polarisationresistances related to the confined area. Owing to its rapidity (in a few seconds per measurement),this technique provides a useful tool for mapping electrochemical characteristics ofreinforcement steel in concrete structures,including half-cell potential,ohmic resistivity andcorrosion rate. These three corrosion-related parameters supply better information to aninspector for condition assessment of reinforced concrete structures. It has been shown from anumber of case applications that the measured corrosion rate is in good agreement with theactual visual observations,while the half-cell potential sometimes may mislead the judgement.Even though the resistivity of concrete alone cannot tell much information aboutreinforcement corrosion,it indeed supplies some information that can help the judgement ofcorrosion conditions when used together with the measurement of corrosion rate.