Monitoring of Water Content in Building Materials Using a Wireless Passive Sensor

Goran Stojanović,Vlastimir Radonjanin,Milan Radovanović,Mirjana Malešev

doi:10.3390/s100504270

Goran Stojanović, Vlastimir Radonjanin + Show 2 more

Open Access

https://doi.org/10.3390/s100504270

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Journal: Sensors (Basel, Switzerland)	Publication Date: Apr 28, 2010
Citations: 52	License type: CC BY 3.0

Affiliation: University of Novi Sad

Abstract

This paper describes an innovative design of a wireless, passive LC sensor and its application for monitoring of water content in building materials. The sensor was embedded in test material samples so that the internal water content of the samples could be measured with an antenna by tracking the changes in the sensor’s resonant frequency. Since the dielectric constant of water was much higher compared with that of the test samples, the presence of water in the samples increased the capacitance of the LC circuit, thus decreasing the sensor’s resonant frequency. The sensor is made up of a printed circuit board in one metal layer and water content has been determined for clay brick and autoclaved aerated concrete block, both widely used construction materials. Measurements were conducted at room temperature using a HP-4194A Impedance/Gain-Phase Analyzer instrument.

Highlights

The measurement of water content in building materials is of particular interest to professionals engaged in maintaining buildings, identifying defects and rectifying possible problems
Apart from the new sensor design, we present the application of this wireless, passive, resonant-circuit for monitoring of water content in building materials, clay brick and autoclaved aerated concrete block, which are widely used in civil engineering
From these data can be observed that the resonant frequency is changed from 35.4 MHz to 33.6 MHz, while the percentage of water absorption in the clay brick is increased from 1% to 17%

Summary

Introduction

The measurement of water content in building materials is of particular interest to professionals engaged in maintaining buildings, identifying defects and rectifying possible problems. Machinery, and the environment, coupled with the efficient delivery of sensed information, could provide tremendous benefits to society [3,4,5]. In the construction industry there is a need to monitor a number of parameters such as the impact of vibration, humidity, material fatigue, and others, to have insight into the building state. In that way it ensures a complete rehabilitation at the time, especially for objects that are vulnerable to environmental influences [10,11,12]

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