Oak wood suppliers in Slovenia are often confronted with belief of consumers, that sapwood is less solid therefore has weaker mechanical properties than heartwood. The aim of this research was to investigate basic mechanical properties of sapwood and heartwood of oaks that appear most frequently on Slovenian market. We take samples of 26 oak logs prepared to be treated into railway sleepers, from which 16 logs (62 %) were from white oak (either Quercus robur and Quercus petraea) and 10 logs (38 %) were from red oak (Quercus cerris). On samples of sapwood and heartwood bending strength, module of elasticity (MOE), compression strength, Brinell hardness and density were measured. Comparison of measured properties discovered that there are no typical differences between individual categories of oak wood, but showed the statistically significant difference between qualities of white and red oak wood. The results declined the laic opinions of consumers, that mechanical properties of sapwood are worse than mechanical properties of heartwood. The research also showed, that due to variability, the Turkey oak (Quercus cerris) wood could possibly have even better mechanical properties than pedunculate oak (Quercus robur) or sessile oak (Quercus petraea), which is also in contrast with general opinion that characteristics of red oak wood are worse than white oak wood. Results of the research will contribute to better understanding of wood properties variability and more optimal selection and usage of solid oak wood.
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