Eng. Mihaela POROJAN

Contributions to the Study of Physical, Mechanical and Technological Properties of Black Locust Wood

SCIENTIFIC COORDINATOR: Prof.dr.eng. Valentin NASTASE

PhD thesis defended at "Transilvania" University of Brasov - Faculty of Wood Industry, July 2007

Black locust (Robinia pseudacacia L.) is a fast-growing hardwood species, which captured the interest of the world specialists, with a view to the extension of this kind of wood for industrial processing.
The main aim of the present paper was to establish the physical, mechanical and technological properties of black locust wood from Romania, by studying the wood from two different geographic areas (northern part - Carei region and southern part - Arges region). Thus, a completion of reference literature on this wood species was targeted.

The achievement of the foreseen outcome presumed an extensive bibliographical research, theoretical studies, as well as experimental research concerning the structure (proportion of heartwood, annual ring width, proportion of latewood), secondary chemical composition, physical properties (moisture content in green state, density and dimensional stability), mechanical properties (bending strength and MOE, compression strength parallel to grain, shearing strength, splitting strength, Janka, Brinell and Monin hardness) and technological properties (shearing strength of the gluing, specific resistance to milling and sanding) of this wood species.

Based on the obtained experimental results, the following could be concluded:
- black locust wood originating from boh geographic areas has remarkably good dimensional stability, excellent mechanical and technological properties, as well as high natural durability under exterior service conditions;
- by comparing the results obtained for wood originating from the two different areas, it could be noticed that the properties of wood from the north are better; this is mainly due to the higher density, which influences directly all other properties;
- with regard to environmental-friendly impact, black locust presents a special importance due to its extraordinary capacity for soil fixing and improvement.

The performed study pursued the promotion of this wood species into the attention of the consumers of wood as raw material and the increase of black locust usage rate within the manufacturing of furniture and other wood-based products, for inside and mainly outside uses.