Characterization of embeddable potentiometric thick-film sensors for monitoring chloride penetration in concrete

In order to monitor the chloride penetration processes, a potentiometric embedded thick-film sensor was developed. This paper includes the results of research on the characterization of Cl− sensors made of Ag/AgCl resistive pastes (materials, sensitivity and detection limit, reproducibility, reversibility and response time, long-term performance and reliability in the presence of interfering agents). Theoretical expressions have been developed to describe the potentiometric response including the presence of OH− and bromide ions. The study shows that thick-film sensors are able to monitor Cl− activity as a function of the redox potential. Sensors are also capable of providing reliable and continuous real-time information on phenomena related to the progress of the chloride penetration front in concrete specimens. These sensors are a promising tool because thick-film technology allows us to obtain miniaturized, low-cost, robust and stable long-term sensors for Cl− monitoring.