The thesis focused on determining the influences of water on the thickness swelling, bending strength and elastic modulus of the chipboard and the OSB board. The test was conducted by immersing the boards in water for 24 or 240 hours. Following soaking for 240 hours, one batch of test pieces was dried up in a furnace until an absolutely dry condition was achieved. It was then established that the prolongation of exposure time caused the thickness of the boards to increase. Also a higher swelling was observed in the OSB board. However, both boards had more or less uniformly reduced in size. The elastic modulus was similar in both boards in the initial dry state; whereas, the bending strength was higher in the OSB board. Following 24 hours of immersion it was established that the strength and the elastic modulus decreased in both board types. Immersion for 240 hours also resulted in the deterioration of chemical properties, which was more significant in the OSB board. The mechanical properties of previously immersed boards had improved after drying, particularly those of the chipboard.
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