Equivalent circuit model for AC electrochemical impedance spectroscopy of concrete

An equivalent circuit model for AC electrochemical impedance spectroscopy (EIS) of concrete has been proposed, which contains parameters R-CCP, the resistance of the continuously connected micro-pores in the concrete; R-CP, the resistance of the discontinuously connected micro-pores, blocked by cement paste layers in the concrete; C-mat, the capacitance across the concrete matrix; and C-DP, the capacitance of the cement paste layers blocking the discontinuously connected micro-pores in the concrete. The proposed model can successfully explain the experimental phenomena observed by other researchers, such as the emergence of the capacitive loops in high-frequency range, the influences of hydration time, silica fume, water/cement ratio on the loops, etc. (C) 2000 Elsevier Science Ltd. All rights reserved.