Thermally modified mini-CLT panel : anti-swelling efficiency and strength properties
Palokangas, Johanna (2021)
Palokangas, Johanna
2021
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Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:amk-2021061516061
https://urn.fi/URN:NBN:fi:amk-2021061516061
Tiivistelmä
The purpose of the thesis project was to examine the anti-swelling efficiency (ASE), modulus of elasticity (MOE), and modulus of rupture (MOR) of the thermally modified mini-CLT panel. Thermally modified glulam and thermally modified solid timber were tested as control groups in ASE. MOE and MOR tests were implemented to mini-CLT and glulam. The tested mini-CLT panels were prototypes, and the commercial production starts in next few years. The project was commissioned by Abodo Wood Ltd. ASE tests were implemented at Abodo’s facilities. MOE and MOR tests were implemented by a third party in material testing laboratory.
The theory section of the thesis consists of an introduction of Abodo, information about the radiata pine and forest plantations in New Zealand, thermal modification theory and process, and general information of the glulam and CLT manufacturing processes.
The preliminary expectation was that the mini-CLT would swell 0.5% in width wise, which was the main interest regarding testing. The test resulted in a 0.8% +/-0.1% swelling after 14 days immersion to water compared to oven dry width and 0.6% +/-0.1% swelling compared to initial (5.7% MC) width. The mini-CLT swelled the most in thickness (5.4%), which was more than the thickness swelling in control groups.
In MOE and MOR the results regarding the mini-CLT were weak compared to the glulam. The weaker results were due to the orientation of the mini-CLT specimens, which were cut across the grain of the main layers of the board. Hence the mini-CLT panels were bended perpendicular to grain, whereas glulam was tested parallel to grain. Bending strength of wood is known to be significantly higher parallel to grain and there-fore better results for mini-CLT are expected if the specimens were oriented parallel to grain in the main layers of the board.
The theory section of the thesis consists of an introduction of Abodo, information about the radiata pine and forest plantations in New Zealand, thermal modification theory and process, and general information of the glulam and CLT manufacturing processes.
The preliminary expectation was that the mini-CLT would swell 0.5% in width wise, which was the main interest regarding testing. The test resulted in a 0.8% +/-0.1% swelling after 14 days immersion to water compared to oven dry width and 0.6% +/-0.1% swelling compared to initial (5.7% MC) width. The mini-CLT swelled the most in thickness (5.4%), which was more than the thickness swelling in control groups.
In MOE and MOR the results regarding the mini-CLT were weak compared to the glulam. The weaker results were due to the orientation of the mini-CLT specimens, which were cut across the grain of the main layers of the board. Hence the mini-CLT panels were bended perpendicular to grain, whereas glulam was tested parallel to grain. Bending strength of wood is known to be significantly higher parallel to grain and there-fore better results for mini-CLT are expected if the specimens were oriented parallel to grain in the main layers of the board.