Measurement of moisture contents in concrete blocks using fringing field spiral capacitive sensors

Abstract

This work reports the design and development of a fringing field, planar capacitive sensor with spiral configuration for measuring moisture contents in concrete blocks, following printed circuit board technology. This method is non-destructive, non-intrusive, cost effective, and provides rapid results. The performances of the fabricated sensors are evaluated with experiments on three different types of concrete blocks. The measured capacitance values are plotted against moisture contents in concrete blocks, measured following the standard gravimetric method. As moisture contents in concrete blocks increase from 0% to 11.34%, the corresponding interelectrode capacitance, which is a measure of the moisture contents, is found to increase by nearly 74%, providing high moisture content sensitivity for the method. The results of the measurements are presented and the implications of the results discussed in the paper. A comparison of the relevant technical parameters of the present system with those of existing technologies are also presented and discussed.