A mixed experimental–numerical electrical resistivity-based method for moisture content assessment in wood tested using the example of Douglas fir

Abstract

The aim of this paper is to present a mixed experimental–numerical approach to evaluate the moisture content (MC) in Douglas fir samples through the use of electrical resistivity measurements. Elevated MC levels constitute the greatest threat to both physical and mechanical properties in timber structures. A reliable MC estimation process is considered a key to ensuring high durability, a long service life and low maintenance costs. In this study, a measurement system typically employed for electrical prospecting in the field of geophysics has been adapted to determine the electrical resistivity of wood. This approach-based tool is essentially a megohmmeter measuring the electrical resistance of wood using two pairs of needle-shaped probes inserted into the material. For this purpose, specific cables and electrodes have been developed. Using samples conditioned in a climate-controlled room, a number of key factors in MC estimation, such as electrode configuration and temperature, were investigated. These results are analyzed in order to both optimize the experimental protocol for future in situ applications and point out the experimental limitations associated with this measurement tool.