Wooden roof shingles were made from pine (Pinus sylvestris L.) and spruce (Picea abies (L.) Karst.). The natural durability of those wood species is classified as class 4 (non-durable). To improve the durability of roof shingles against basidiomycetes, they were impregnated or hydrothermally modified. Impregnation was done with one of two commercially available preservatives – Celcure AC 500 or Dikants. Celcure AC 500 is a copper based preservative, whereas Dikants is chrome-fluorine-boron based. Shingle impregnation with Celcure AC 500 was done in two ways – by dipping and vacuum treatment; impregnation with Dikants was done by dipping. After impregnation, all roof shingles were coated with linseed oil. Hydrothermal modification was done in two regimes – 150°C/3 h and 160°C/1 h. To determine the efficiency, impregnated or thermally modified roof shingles were tested according to the standards EN 113 (G. trabeum) and EN 84 (C. puteana, G. trabeum and P. placenta).
The first durability class was reached almost for all preservation strategies, except the case of impregnation with Celcure AC 500 by dipping for spruce, where the mass loss was 5.1%. The best results according to EN 113 were obtained for spruce, hydrothermally modified at 150°C/3 h and the Celcure AC 500 vacuum treated pine (amount of the chemical preservative 3.3 kg/m3) – both showed a mass loss of 1%. The results of the tests according to EN 84 indicated that none of the chemical preservatives after leaching was effective against C. puteana. Heat treatment was more effective than chemical treatment, and pine gave better results than spruce. For pine, the first durability class was reached in both the hydrothermal modification regimes, but spruce reached the first durability class when it was modified at 160°C/1 h.
Keywords: decay resistance, heat treatment, Celcure AC 500, Dikants
Authors
Janberga A.
Latvian State Institute of Wood Chemistry, Riga, Latvia
Irbe I.
Latvian State Institute of Wood Chemistry, Riga, Latvia
Kurnosova N.
Latvian State Institute of Wood Chemistry, Riga, Latvia
Andersons B.
Latvian State Institute of Wood Chemistry, Riga, Latvia
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