Moisture monitoring in glulam timber structures with embedded resistive sensors: study of influence parameters

Uwizeyimana, Placide; Perrin, Marianne; Eyma, Florent

doi:10.1007/s00226-020-01228-8

Cited by 11 publications

(3 citation statements)

References 25 publications

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“…Studies have been carried out regarding the electrical properties of wood which has a moisture content of below the FSP (fibre saturation point), most notably in the following research items: (Stamm, 1927;Skaar, 1964Skaar, , 1988Vermaas, 1975;Norberg, 1999Norberg, , 2000Forsén & Tarvainen, 2000;EN 13183-2:2002EN 13183-2: , 2002Brischke & Rapp, 2008;Björngrim et al, 2017;Li et al, 2018;Uwizeyimana et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Investigation and modelling of the electrical charging effect in birch wood above the fibre saturation point (FSP)

et al. 2022

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Wood moisture content (MC) has a significant impact on all electrical properties of wood. Regarding the development of the (so-called polarization-type) wood moisture meter with the electrical charging effect for monitoring and controlling the wood drying process, it is of interest to expand the theoretical background of this type of novel wood moisture meter by means of modelling. Two mediums were selected for modelling – raw birch wood and, as a reference medium, birch liquid sap – into which two symmetrical carbon fibre measuring electrodes were inserted. In both mediums, direct current and alternating current were passed between electrodes at different electrode potentials. The electrical field and electrical response of the current-affected mediums were then measured and modelled in the time domain and frequency domain. The numerical results of modelling are comparable both in the time domain and frequency domain (i.e. if E = 1.8V, then Cs = 0.5 mF and C1,int = 0.7 mF). The concept of energetic chargeability (CHA(W)) of wood was defined and compared to conventional chargeability as defined by C. Schlumberger in 1913. Empirical dependencies of CHA(W) on electrode potential and primary energy W1 transmitted through the wood (sap) medium were found. In the frequency domain, frequency dependencies were found to distinguish between adsorption processes and mixed kinetics ranges in birch sap and in raw birch wood.

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Section: Introductionmentioning

confidence: 99%

Investigation and modelling of the electrical charging effect in birch wood above the fibre saturation point (FSP)

et al. 2022

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“…In practice, the direct current (DC) electric resistance method (Stamm, 1927;Tamme et al, 2012;Uwizeyimana et al, 2020) for determining and monitoring wood moisture content is widely used, as it is an inexpensive and reliable method for use both at room temperature and in harsh kiln conditions (Gann, 2021;Scanntronik, 2021;Brookhuis, 2021;BES Bollmann, 2021;etc.). However, the main disadvantage of the DC resistance method is that the MC readings obtained by this method are not reliable above FSP (ca.…”

Section: Introductionmentioning

confidence: 99%

Comparative testing of two alternating current methods for determining wood moisture content in kiln conditions

et al. 2021

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Research into the possibility of applying the electric impedance spectrometry (EIS) method and the dielectric capacitance method (DECM) simultaneously above fibre saturation point (FSP) and in harsh kiln conditions has been relatively scarce. In the framework of this research, tests were carried out on the operational reliability of the measuring capacitor (MEC) prototype used for calibrating the DECM in the harsh internal climate (50°C and 98% RH) of the kiln. Condensation of water vapor on MEC plates, leakage of MEC insulators and the emergence of static electric charges on MEC plates were studied. Quantitative ranges were found for MEC performance-disrupting effects on the parasitic capacities induced by each effect. The DECM was found to be less reliable than the EIS method for application in harsh kiln conditions. Secondly, under the same test conditions and for the same wood species (birch), the possibilities of the DECM method and the EIS method were comparatively modeled with the predetermined Rozema quality criterion of ±1.75% MC for predicting the moisture content (MC) of birch wood above FSP. It was found that, under the same test conditions, the DECM method proved more accurate than the EIS method for predicting birch wood MC above FSP. Based on the tests, it was concluded that DECM can be used in practice by applying a non-destructive method to reliably determine the average moisture content of a wood batch immediately prior to commencing the wood-drying process.

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“…The effect other factors have on MC measurements is generally known through literature therefore they were not examined in this literature review. For example, several studies have found that the electrical resistance of wood decreases when its temperature increases [27][28][29][30][31].…”

Section: Factors Impacting Electrical Conductivity In Woodmentioning

confidence: 99%

A Statistical Approach for Determining the Impact of Sensor Orientation and Electrode Type on Moisture Content Measurements in Eastern White Pine

Daouk¹

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As buildings become more airtight and insulated, the movement and accumulation of moisture within building envelopes become paramount in determining its resiliency.Current methods for quantifying the moisture content (MC) of wood species involve the measurement of electrical resistance between two installed electrodes and the use of existing empirical correlations to evaluate the MC. However, these correlations do not adequately consider the impact of sensor orientation and electrode type within wall assemblies. The aim of this study was to statistically examine the impact of sensor orientation and electrode geometry on MC measurements in 126 eastern white pine samples with electrodes placed along and across the grains of the wood using six different fasteners. Samples were placed in a controlled environmental chamber until steady state was achieved at three relative humidity (RH) levels. Oven-dry MC measurements were taken and electrical resistances were measured in both directions as samples reached steady state at each RH level (73.3%, 85%, and 92.5%) at temperatures ranging from -10℃ to 40℃. Based on the homogeneous nature observed from statistical t-tests, it was determined that sensor orientation does not have a significant impact on MC measurements (p>0.05) and therefore does not need to be considered. Additional t-tests and multivariate regression analyses using Pfaff and Garrahan's empirical MC equation showed that fasteners similar in geometry to 2.1mm stainless steel nails require a unique set of regression coefficients (p<0.05) to minimize overall 𝑅𝑀𝑆𝐸 from 1.81%MC to 0.79%MC. A different and more general set of regression coefficients was developed for the other 5 fasteners to minimize the overall 𝑅𝑀𝑆𝐸 from 1.15%MC to 0.85%MC. When using electrodes and regression coefficients that are incompatible, errors associated with MC can reach up to ±2% MC.

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Moisture monitoring in glulam timber structures with embedded resistive sensors: study of influence parameters

Cited by 11 publications

References 25 publications

Investigation and modelling of the electrical charging effect in birch wood above the fibre saturation point (FSP)

Investigation and modelling of the electrical charging effect in birch wood above the fibre saturation point (FSP)

Comparative testing of two alternating current methods for determining wood moisture content in kiln conditions

A Statistical Approach for Determining the Impact of Sensor Orientation and Electrode Type on Moisture Content Measurements in Eastern White Pine

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