EVALUAREA COMPARATIVA A PATRU METODE DE CLASIFICARE A DURABILITATII NATURALE A LEMNULUI DUPA O PERIOADA DE EXPUNERE DE 2,5 ANI

Per Otto FLÆTE
Cercetator - Norwegian Forest and Landscape Institute
Adresa: PO. Box 115, 1431 Ås, Norway
Tel: 0047 64948000. Fax: 0047 64948001.E-mail: Per.Otto.Flate@skogoglandskap.no

Gry ALFREDSEN
Cercetator - Norwegian Forest and Landscape Institute
Adresa: PO. Box 115, 1431 Ås, Norway
Tel: 0047 64948000. Fax: 0047 64948001.E-mail: Gry.Alfredsen@skogoglandskap.no

Fred EVANS
Cercetator - Norsk Treteknisk Institutt, Postboks 113 Blindern, 0314 Oslo, Norway
Tel: 0047 64948000. Fax: 0047 64948001.E-mail: Fred.Evans@treteknisk.no

Rezumat:
In Norvegia structurile de lemn din exterior sunt realizate in mod traditional aproape exclusiv din lemn tratat sau netratat de molid (Picea abies) si pin (Pinus sylvestris). In ultimii ani se inregistreaza o tendinta de a utiliza si alte specii, cum ar fi diferite foioase indigene si specii din import, in aplicatii ale lemnului in conditii de exterior, deasupra solului, acest lemn fiind utilizat adeseori nefinisat. Pentru multe specii, cu precadere foioase, lipsesc insa informatiile privitoare la durabilitatea in utilizari corespunzatoare clasei 3 de risc biologic. Principalul obiectiv al acestei lucrari este evaluarea durabilitatii naturale a unor specii lemnoase norvegiene in conditii de exterior deasupra solului (clasa 3 de risc biologic) si a compara rezultatele obtinute prin doua metode nestandardizate de testare cu cele conform testelor standardizate in contact cu solul (EN252) si metodei de laborator de evaluare a performantei fata de basidiomycete (EN113).
Testele conform normelor europene EN 113 si EN 252 au dat rezultate aproape similare, acestea corespunzând de asemenea cu clasificarea durabilitatii naturale conform EN 350-2. Rezultatele celor doua teste nestandardizate deasupra solului au fost insa oarecum diferite fata de EN 113, EN 252 si EN 350-2. Acestea au aratat ca pentru o aceeasi specie clasificarea durabilitatii naturale poate fi diferita in functie de clasa de risc corespunzatoare utilizarii. Totusi, incercarile in teren trebuie continuate pentru o perioada mai lunga de timp inaintea stabilirii definitive a clasei de durabilitate naturala. Patru specii ce nu sunt incluse in EN 350-2 au fost clasificate din punct de vedere al durabilitatii naturale prin acest studiu: Juniperus communis (1), Salix caprea (5), Sorbus aucuparia (5) si Populus tremula (5).

Cuvinte cheie: comparare metode, durabilitate naturala, specii norvegiene, metode de testare.

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