Non-destructive inspection of chloride ion in concrete structures using millimeter wave attenuated total reflection technique

We have developed a millimeter wave (MMW) attenuated total reflection (ATR) system for the measurement of chloride ion (Cl^-) concentration in concrete structures. Concrete samples with different Cl^- concentrations were prepared and their reflectance were measured. The experimental results showed that reflectance decreased almost linearly with the increase in Clconcentration. This result demonstrates that MMW could be used for the non-destructive inspection of Cl^- concentration in concrete structures.