Evaluations of the deterioration characteristics of thermally treated wood samples from Corymbia citriodora and Eucalyptus urophylla caused by marine wood borers

Abstract

The low natural durability properties of some types of wood indicate the need for treatments to enhance the resistance of these materials to biological decay. In the sea, this resistance is necessary due to the actions of wood-boring mollusks and crustaceans. These treatments must be effective without harming the environment. Wood thermal treatment should be evaluated for this purpose. Therefore, the aim of this study was to evaluate the deterioration characteristics of thermally treated wood samples from Corymbia citriodora and Eucalyptus urophylla under the actions of marine wood borers. A method was proposed to aid in this assessment. Ten samples of these woods, both untreated and thermally treated, were submerged in the sea, each at a depth of 2.5 meters, for five months. After this period, the external borehole number, mass loss, and central flat lesion parameters of the samples were evaluated. Both the thermally treated and untreated wood samples of C. citriodora showed less deterioration than those of E. urophylla, with fewer boreholes, smaller lesioned areas, and lower mass losses. Compared with untreated wood and E. urophylla wood, thermally treated C. citriodora wood exhibited some resistance to marine wood borers. It was concluded that C. citriodora wood was naturally more resistant to marine wood borers than E. urophylla wood. Moreover, thermal treatment increased the boring resistance of C. citriodora wood while increasing the susceptibility of E. urophylla wood. The digital measurement of flat lesions was proven to be an auxiliary and promising method for evaluating the deterioration process.