Wood Density and Moisture Content Estimation by Drilling Chips Extraction Technique

Abstract

The novelty of this study is the development of an accurate wood moisture content (MC) estimation method based on a relatively brand-new, non-destructive testing technique (drilling chips extraction). The method is especially important in the assessment of existing timber structures, where non-destructive testing (NDT) results are affected by wood MC and should be adjusted to a reference MC, usually 12%. In the assessment of timber structures, it is not possible to determine MC by oven drying method and this should be estimated. Electrical resistance and capacitance are the conventional methods used for MC estimation. This research work aims to present an accurate MC estimation method based on the drilling chips extraction technique. For that, 99 specimens (90 × 65 × 38 mm3) from three softwood and hardwood species covering a wide range of densities (from 355 to 978 kg m−3) were tested after conditioning at five different MCs (5%, 10%, 15%, 20%, 25%). The Wood Extractor device based on the drilling chips extraction technique was used. The mass of the chips collected (drilling residue) from each drill was recorded. The results show that the MC of the chips extracted was statistically significantly different than the MC of the specimen and cannot be directly used as MC determination. However, the chips MC can be used as an estimator of specimen MC with high determination coefficients (R2 from 71% to 86%). As the main result, models to estimate density directly adjusted to a reference 12% MC from the wet and dry mass of chips extracted were developed with an R2 of 98%. In sum, the drilling chips extractor is a dependable and straightforward method to estimate MC and density from only one measurement. Density adjusted to a reference 12% MC can be directly estimated from a single model.

Numerical and Experimental Analysis of the Load-Carrying Capacity of a Timber Semi-Rigid Dowel-Type Connection

“…It is possible to use selected non-destructive experimental testing, as in Nowak 2019 [ 30 ] and Nowak 2021 [ 31 ]; dynamic testing, as in Bragov 2020 [ 32 ]; and the non-destructive vibrational method described in Olaoye 2021 [ 33 ] in order to determine these mechanical properties. A semi-destructive method can also be used to determine the density and moisture content of timber, as described in Martínez 2020 [ 34 ].…”

The Review of New Scientific Developments in Drilling in Wood-Based Panels with Particular Emphasis on the Latest Research Trends in Drill Condition Monitoring

“…In parallel, new research on improving the drilling resistance measurements as a semi-destructive method of assessing the condition of the existing timber structures are still being carried out [11][12][13]. Likewise, a method of estimation of wood density and/or moisture content by drilling chips extraction technique is constantly being improved [14][15][16][17]. Similarly, the advanced scientific studies on the development of drilling-based tests (which are increasingly and commonly considered the most convenient-the quickest and most material-saving-methods of machinability rating of any wood-based materials) has been carried out recently [18][19][20].…”