Study of the effect of extractives on the natural durability of Eucalyptus bosistoana wood

IRG/WP 18-10928

M Ibáñez, C Mantero, N Silva, F Resquín

Wood as a natural material is degradable both by biotic deterioration agents (fungi, bacteria, marine borers, insects) and abiotic (UV and IR radiation, moisture, fire, etc.). The inherent resistance to the attack of the deteriorating agents is defined as the natural durability of the wood. This is an important property when considering the shelf life of wood products exposed to extreme conditions, which together with the physical, mechanical and aesthetic character of the wood define its use. It is a complex phenomenon involving factors such as wood density, chemical composition, particularly the lignin content, and extractives (quantity and type), anatomical characteristics, sapwood / heartwood ratio and others, like environmental factors, growth factors, silvicultural interventions, origin, genetics, and age. Among these factors, the content of extractives plays a relevant role. The EN 350-1: 1994 standard defines the requirements for determining the natural durability against fungi, and other biotic agents and describes the classification of durability. In this work we study the effect of extractives of the heartwood of Eucalyptus bosistoana on its durability against a white rot fungus, Coriolus versicolor and a brown rot, Gloeophyllum trabeum. E.bosistoana is reported in literature as a high durability species, it is grown in Uruguay in small areas, and is considered as a species with significant potential for some industrial applications, such as construction. For the study the wood grown in different sites, were exposed to the fungi in accordance with EN 113: 1996, before and after removing the extractives with water and with hexane. At the same time, the fungicidal activity of the extracts obtained in both solvents, was evaluated facing the same rot fungi. The biocidal efficacy of the extracts and their influence on the durability of the wood were verified. Finally the wood was heated to 240 ° C during different times and its durability was evaluated, exposure to heat as in a drying or weathering process affects the content of volatile extractives decreasing the durability.

Keywords: Eucalyptus bosistoana, natural durability, extractives

Conference: 18-04-29/05-03 Johannesburg, South Africa

Purchase this document