Developing a Multi-Element Sensor to Non-Destructively Monitor Several Fundamental Parameters Related to Concrete Durability

A design scheme of multi-element sensor which included electrical resistivity probes, multiple Cl(−) selective electrodes, and a steel corrosion monitoring system was proposed in this work. Embedding this multi-element sensor in concrete enables the real-time and non-destructive monitoring of internal electrical resistivity, free Cl(−) (Cl(f)) contents in the concrete pore solution at different depths, and steel corrosion parameters. Based on the monitoring data obtained by the multi-element sensor, the freezing-thawing (F-T) damage degree, the Cl(f) diffusion coefficient, the quantitative relation between F-T damage degree and Cl(f) diffusion coefficient, the initiation period of steel corrosion, and the critical content related to steel corrosion are determined. To conclude, the multi-element sensor provides key durability parameters for the establishment of the Cl(f) diffusion model, the assessment of health condition, and the prediction of service life of concrete under the coexistence of the F-T cycle and Cl(−).