Error evaluation and correction of stray impedance during measurement and interpretation of AC impedance of cement-based materials

In this study, the error of stray impedance during measurement and interpretation of the AC impedance of cement-based materials was evaluated based on a proposed reasonable correction method. The results indicated that the stray impedance produces approximately 60% and 35% modulus errors at 15 MHz frequency, and 1.68–55.30% and 10.72–153.58% errors of the interpreted parameters for 210-d and 3-d curing concrete, respectively. The stray impedance of the two electrodes and the extra shorting wire introduced in the traditional correction method (Zei) produce approximately 45% and 15% modulus errors at 15 MHz frequency, and 0.94–82.81% and 49.03–96.71% errors of the interpreted parameters for 210-d and 3-d curing concrete, respectively. The proposed method eliminates the Zei and contains only extra introduced contact resistance between the shorting wire and the two electrodes (Rcls). However, the Rcls produce less than 1% modulus and the interpreted parameters errors, indicating that the proposed method is accurate.