Effects of white rot and brown rot decay on the drilling resistance measurements in wood

Abstract

AbstractAn IML-RESI PD 400 drilling tool and a standard spade drill bit (IML System GmbH, Wiesloch, Germany) were used to study the impact of white and brown rot decay on drilling resistance (DR) measurements in wood. In total, 720 drillings were made in specimens of Scots pine (Pinus sylvestrisL.) heartwood and sapwood, European beech (Fagus sylvaticaL.) and English oak (Quercus roburL.), which were decayed byConiophora puteanaandTrametes versicolor. Drillings were made with specimens conditioned in normal climate (20°C/65% RH) and with specimens vacuum-impregnated in water. DR and feeding force (FF) were negatively correlated with mass loss (ML) due to fungal decay. The intensity of reduction was higher for DR than for FF with increasing ML for all decay types and moisture contents (MCs). A significant difference (at 95% confidence level) in DR was found between decay types using water-saturated (WS) Scots pine specimens (3–35% ML). In most cases, DR revealed a higher predictive power of the models for ML prediction than FF. Free water in decayed specimens significantly reduced the DR and FF. Hence, the effect of ML on DR and FF of decayed and WS wood was less prominent.