STUDY ON MULTIPLE PARALLEL EQUIVALENT CIRCUITS USED FOR AC IMPEDANCE ANALYSIS

Abstract

A number of equivalent circuit models have been proposed so far. It has been reported that it is possible to understand the porosity and progress of hydration of hydrated cement from obtained AC parameters even in the classical model. In this paper, a multiple parallel equivalent circuit model is proposed, focusing on the number of different time constants that appear in the equivalent circuit, which is assumed to be related to the complexity of the pore structure of the hardened cement. The ultimate goal is to establish a relationship between the number of time constants and the pore structure of hardened cement. As a first step, we measured the AC impedance of mortar sensors to determine the number of time constants. The measured AC impedance of the mortar sensors was approximated by impedance calculated from equivalent circuits with a finite number of parallel circuits. Some of the time constants were retained even when water content changed.