The density and some mechanical properties associated with the ageing of wood were investigated. We have sampled oak construction wood (Quercus spp.) from four years to 512 years old with known dendrochronological data. On 31 selected discs of old oak, the speed of ultrasound and the stiffness of the wood in all anatomical directions of wood were measured in laboratory conditions. With static tests, the hardness transverse to the grain and the shear strength parallel to the grain were tested as well. Depending on the age of the wood, uneven changes in the density of wood, shear strength of the wood, the speed of ultrasound and dynamic stiffness in all anatomical directions of wood have been observed. The highest stiffness of oak wood was determined parallel to the grain. Similar results, but four times smaller, were determined in the radial and tangential directions. The trend of a slow decrease in value with oak aging that is statistically insignificant was found in the hardness of the wood transverse to the grain, and in radial and tangential directions. The ratio of hardness and density of the wood, known as the specific hardness, was somewhat lower in the old oak than the recent oak wood.
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