INFLUENCE OF CYCLIC FREEZING AND THAWING UPON SPRUCE WOOD PROPERTIES

The paper presents the results concerning the change of some physical and mechanical properties of spruce wood (Picea abies L.), after repeated freezing and thawing, respectively after being subjected to temperature variation from positive valuea (+100C) to negative values (-250C). Through this approach, the authors aimed at simulating normal temperature variations that occur in winter between night and daytime and which fresh cut timber has to stand if being stored in an open yard for one week before being kilndried. By comparing these results with the ones obtained after continuous freezing at -250C for one week, it was established that the temperature variation and the repeated changing phase of water inside wood increase dimensional instability and reduce the mechanical strengths much more than the simple exposure to theconstant negative temperature.