Résumé
The role of wood extractives on the physical behaviour and the durability was investigated for four timbers from Cameroon: mansonia, bubinga, moabi and padauk. Physical properties such as density, shrinkage (tangential, radial and total), fibre saturation point and colour were measured on solid wood samples before and after two successive soxhlet extractions using ethanol-toluene (1-2 v/v) and boiling water. The influence of extractives on wood natural durability was carried out by testing crude and extracted sawdusts against the activity of termites (Reticulitermes santonensis). The extractions were performed as for the solid wood samples, and the sawdust was tested after the first and the second extraction. Extraction rates have been calculated for each set of extractions. In each case, sawdust was compacted into a disc and place in a petri dish (containing wet sand as a medium) with 50 termite workers, one nymph and one soldier. A daily observation was done, and after five weeks the termite survival rates in the test petri dishes were compared with the controls. The results obtained showed that the wood extractives play an important role in the physical properties (especially in the shrinkage) as well as in the durability against termites. (Résumé d'auteur)