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- Title
PERFORMANCE OF HEAT-TREATED AYOUS WOOD AFTER ONE YEAR OF OUTDOOR EXPOSURE.
- Authors
Lo Monaco, Angela; Gennari, Emiliano; Picchio, Rodolfo
- Abstract
Wood is an interesting material especially when used outdoors where it is exposed to weathering and degradation. Heat treatment of wood has proved to be an ecological way for outdoor use which is particularly useful in the case of less durable wood, it is also a non-biocidal alternative to the classical techniques of prolonging the natural durability of wood. Heat treatment decreases hygroscopicity which guarantees a lower sensitivity of the wood material towards environmental variations both of moisture and temperature. In this context, it is essential to check the behavior of heat-treated wood over time. The aim of this work was to verify the effects of the natural aging process on some physical properties of heat-treated Ayous (Triplochiton scleroxylon K. Schum) wood. The wood of this species becomes increasingly attractive on the international market due to the rapid growth of the trees and easy wood processing. The material used in the study comes from certified forests for sustainable management that grow in Cameroon. The Ayous planks were donated by Vasto Legno, the company also submitted the planks to heat treatment at an industrial plant. The heat treatment was carried out at 215°C for three hours with a slight initial vacuum. The planks, treated and untreated, were exposed outdoor conditions for one year. A statistical analysis has shown that the density of heat-treated aged wood remains significantly lower than the untreated aged wood. Compared to environmental humidity, the heat-treated wood reaches a consistently lower moisture content than the untreated wood that indicates an appreciable dimensional stability of the material. Even after 12 months a lower ability to absorb moisture than the untreated wood was retained. The anti-shrinkage efficiency (ASE) value supports this improvement. However, the ASE value was found to be below 75%-threshold, which is indicated as the minimum effective threshold. Colour is an important factor which affects the aesthetics of wooden products. Heat treatment induced darkening, measured by the chromatic coordinates' values and was clearly visible even to the naked eye on the naturally light-yellow colour of the ayous. The colour variation indicates chemical modifications, and lignin degradation contributes to the darkening of wood. The natural aging process causes a colour variation as well, both in the untreated and in the treated wood. In the natural wood there was a darkening of the surface, and the plank surface acquired a greyish colour/hue. The heat-treated wood was darkened by the treatment rather than turning lighter. Natural aging of wooden surfaces leads to a slow deterioration of wooden surfaces, which cause unwanted changes. However, the process is worth investigation after longer exposure times.
- Subjects
CAMEROON; WOOD; WOOD products; HEAT treatment; TREE growth; FOREST management; WOOD density; FACTORIES
- Publication
ACTA Scientiarum Polonorum Silvarum Colendarum Ratio et Industria Lignaria, 2022, Vol 21, Issue 4, p358
- ISSN
1644-0722
- Publication type
Article