This study evaluated biological resistance, water absorption, and total carbohydrate contents of carbonized woods by contact charring method followed by linseed oil submersion. Charred and control specimens were exposed in laboratory fungal resistance tests to two white – and two brown-rot fungi and in mold resistance tests by spraying the surface with a mold spore-suspension comprised of three different mold species. Charred and control specimens were also evaluated for resistance to the eastern subterranean termites. To help understand biological durability results, carbohydrate content and water absorption of test specimens were also determined. In all cases, durability against wood degrading fungi increased with the exception of charred Eucalyptus bosistoana wood exposing to the white-rot fungus, Irpex lacteus. Mold resistance of charred Pinus taeda specimens increased considerably when compared to controls however, no mold growth was observed on either control or charred specimens of E. bosistoana. In termite tests, significantly less weight losses were shown in charred specimens of both wood species tested compared to controls although, no complete protection was achieved against termite attack. Total carbohydrate content of charred wood specimens decreased after the carbonization process and as expected, increased hydrophobicity was observed with >50% less water uptake in charred specimens.

The organic nature of wood makes it susceptible to abiotic and biotic degradation. Impregnation with chemical products is the most common method of protection. Only inorganic borates combine the unique set of properties that make them well suited for wood protection: they are insecticidal, fungicidal and flame retardants. In this work, zinc borate is suspended in an ammonia solution and applied in depth to wood. Its resistance to leaching is evaluated. The product is tested against rot fungi (Gloeophyllum trabeum and Trametes versicolor) and a xylophagous insect (Anobium punctatum). The results verify its effectiveness as a wood protector, while leaching less than other borate-based products.

Pinus elliottii Engelm bark is a byproduct of Uruguay’s milling industry. As a circular economy strategy, it is burned in broilers for energy production. Aiming to increase the added value of the bark, this work analyzes the extraction of its tannins to use them in the development of formaldehyde-free adhesives, while evaluating whether it retains its calorific power for further energy production. The best extraction conditions (methanol at 65 °C for 2 h) were identified at a laboratory level after which they were scaled up to 50 L, which did not affect extraction yield. The Stiasny number remained above 65%, meaning the extractive was suitable for its use in adhesive formulations. The characterization of the extractives was completed with molecular weight distribution, FTIR-ATR, ABES and DSC. Finally, two formaldehyde-free adhesive formulations were developed using hexamine and glyoxal as hardeners. Their behaviors were compared through rheological analysis, DSC and ABES. It was determined that the adhesive formulations with hexamine at pHs of 8 and 10 are suitable for their use in the timber industry. It was noted that they react the best at a pressing temperature of 160 °C. After the extraction, the calorific power of the P. elliottii Engelm bark decreased by only 13%, thus remaining useful for energy production.

Owing to its physico-mechanical properties, wood is widely used in housing for both outdoor structures and indoors in floors, ceilings and others. However, its vulnerability to fire makes protection necessary for occupant safety and damage prevention. In this study, the fire performance of Pinus taeda (loblolly pine) wood from northeastern Uruguay treated with zinc borate synthetized in our laboratory is tested. The effect of leaching on zinc borate fire retardant properties was also evaluated. The following parameters associated with the thermal degradation process of wood were analyzed: flame spread, carbonized area, carbonization index and mass loss. The wood was radially and tangentially exposed to the flame in a Vandersall tunnel under controlled conditions for three exposure times: 30, 60, and 80 seconds. The micromorphology of the surfaces exposed to the flame at each exposure time was analyzed with a scanning electron microscope in order to evaluate fiber damage, zinc borate distribution within the wood, and the effects of leaching on fire performance. A clear improvement in the fire resistance of the zinc borate -treated wood could be verified for all exposure times; leaching did not affect its fire retardant properties despite the harsh conditions of the test, making the product potentially suitable for outdoor use.