Investigation on the performance characteristics of chloride selective electrode in concrete

A monitoring technique based on the chloride selective electrodes for the chloride content in concrete which is accurate, non-destructive, and continuous would be highly desirable. For this reason, the performance, such as Nernst response and resisting polarization, of the electrode was tested both in simulated concrete pore solutions and concrete. Moreover, the surface morphology of electrode after immersion in solutions over 3 months was detected. Results revealed that the electrode potential showed a good Nernst response with chloride concentration and was affected little by sulfate ion. The detection limit for the chloride concentration was 10 −3 mol L −1 at pH 13.5 and 10 −4 at lower pH values. In addition, the electrode also had a high exchange current density and a high equivalent capacitance. The Ag/AgCl coating showed good long-term stability over 3 months in solutions containing chloride ions. Besides, there was a good agreement between the free chloride content determined by the electrode and by pore solution expression.