Rot-type specific impact of fungal decay on the structural integrity of wood

Felle, Tim Konrad (author), Humar, Miha (mentor)

Wood-destroying fungi cause different types of decay which lead to a reduction of various elastomechanical properties of wood. This is already significant when the mass loss is not yet gravimetrically detectable. Particularly difficult to define is the incipient decay, since the reduction of elastomechanical properties is highly dependent on the heterogeneity and variability of individual wood species. In this study two wood species that are prescribed in several standards of determination of wood durability against wood-destroying fungi have been used, i.e. European beech (Fagus sylvatica L.) and Scots pine (Pinus sylvestris L.) sapwood. Specimens of 10 (long.) × 5 × 20 mm3 have been incubated with white-rot (Trametes versicolor) and brown-rot (Coniophora puteana) fungi and with different soft-rot fungi (spore suspension) for various incubation times. After incubation the moisture content and relative mass loss have been measured. The High-Energy Multiple Impact (HEMI) – test is a reliable tool to detect the incipient decay, thus the specimens were tested and the value of structural integrity (Resistance to Impact Milling) depending on the mass loss were determined. The reduction of structural integrity was compared with the reduction of different strength properties of wood (Impact Bending Strength, Modulus of Rupture) depending on the mass loss. The fracture patterns after HEMI – test have been investigated with a digital microscope. The DVS (Dynamic Vapor Sorption) method has been used to investigate the sorption properties of the decayed specimens.

• Language: English
• Keywords: white rot, brown rot, soft rot, High-Energy Multiple Impact (HEMI) test, structural integrity, Dynamic Vapor Sorption
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Publication date: 27.07.2023
• Publisher: [T. K. Felle]
• Year: 2023
• Number of pages: X, 56 str.
• PID: 20.500.12556/RUL-148041
• UDC: 630*844.2
• COBISS.SI-ID: 159858947
• Publication date in RUL: 26.07.2023

Secondary language

• Language: Slovenian
• Title: Vpliv tipa glivnega razkroja na strukturno celovitost lesa

Abstract

Glive razkrojevalke povzročijo trohnobe, zaradi katerih les izgubi vrsto elasto-mehanskih lastnosti. To je mogoče zaznati že takrat, ko izgube mase lesa, zaradi razkroja, še ni mogoče gravimetrično določiti. Posebno težko je zaznati začetni razkroj, saj je izguba elasto-mehanskih lastnosti močno odvisna od heterogenosti in variabilnosti lesnih vrst. V tej raziskavi sta bili uporabljeni lesni vrsti, ki sta predpisani v več standardih za določanje odpornosti lesa proti glivam razkrojevalkam in sicer, navadna bukev (Fagus sylvatica L.) in beljava rdečega bora (Pinus sylvestris L.). Vzorci dimenzije 10 × 5 × 20 mm3 so bili inkubirani z glivami bele (Trametes versicolor) in rjave (Coniophora puteana) trohnobe ter kombinacijo gliv mehke trohnobe (suspenzija gliv) v več časovnih intervalih. Po inkubaciji sta bili določeni vsebnost vlage in relativna izguba mase. High-Energy Multiple Impact (HEMI) – test je zanesljiv pri zaznavanju začetnih stopenj razkroja, zato so bili vzorci testirani in jim je bila določena stopnja strukturne celovitosti (Resistance to Impact Milling) glede na izgubo mase. Izguba strukturne celovitosti je bila primerjana z izgubami drugih mehanskih lastnosti (Impact Bending Strength, Modulus of Rupture) v odvisnosti od izgube mase. Z digitalnim mikroskopom so bili testirani vzorci lomov po HEMI – testu. Vzorcem so bile z DVS (Dynamic Vapor Sorption) metodo določene sorpcijske lastnosti.

• Keywords: bela trohnoba, rjava trohnoba, mehka trohnoba, High-Energy Multiple Impact (HEMI) test, strukturna celovitost, Dynamic Vapor Sorption