Wood is a hygroscopic material and its moisture content varies in dependence of surrounding. Major influence on moisture content of wood has relative humidity of surrounding, while temperature effect is less significant. In this work wood moisture changes in dependence on air conditions have been investigated.
Samples were cut from the pine wood. Pine trunk was divided in the four zones: I zone was near the stump, II zone was 3.2-3.7 m from the stump, III zone was located 6.3-6.8 m from the stump and the IV zone was in the distance of 9.5-10 m from the stump. In perpendicular direction wood was divided in the three zones: heartwood, in-between from heartwood to sapwood and sapwood. From the each group 12 samples were prepared. Half samples were kept outdoors in the meteorological boxes and the rest part of samples was placed indoors. Specimens dimensions in radial, tangential and longitudinal directions were respectively 35, 50 and 270 mm, initial moisture content of samples was about 9-10%. Average conventional wood density was 385-414 kg/m3. Samples weight and air parameters were fixed once a week.
It was found that wood sorption properties depend on the sample place in the trunk. For indoor placed samples from sapwood moisture variation was 0.19-0.21% and for outdoors it was from 0.75 up to 0.86%. Samples prepared from the core it was 0.15-0.17% for indoors placed samples and 0.6-0.72% for outdoors ones. The highest moisture content was found for the IV zone timber, i.e. 7.7-8.4% for indoors placed samples and 15.6-15.9% for outdoors placed samples. The lowest moisture content was found in zone I (14.8-15.4%) and zone III (7.7-7.9%). The highest variation amplitude of moisture was found for the sapwood (1.2-1.3% indoors, outdoors 5.3-5.8%), the lowest for the core wood (from 4.1 up to 4.8 % and from 1.0 up to 1.2% respectively for indoors and outdoors). It was found that intensity of moisture changes for outdoors placed samples was four times higher than those of placed indoors.
Keywords: pine wood, moisture content, heartwood, sapwood
Authors
Bridziulaitytė V.
Department of Materials Engineering, Kaunas University of Technology, Kaunas
Juodeikienė I.
Department of Materials Engineering, Kaunas University of Technology, Kaunas
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