Analysis of the reasons for the degradation of impregnated wooden posts

Les v zadnjem času pridobiva na veljavi kot gradbeni material. Ko ga uporabljamo za gradbene namene, želimo, da lesni izdelki čim dlje časa obdržijo funkcionalnost. Še posebej zunaj vgrajen les je izpostavljen lesnim škodljivcem, če pa je poleg tega še v stiku z zemljo, pa je ogroženost še večja. Leseni koli, ki smo jih preučevali v diplomskem projektu so bili zabiti v zemljo na otroškem igrišču v Ljubljani. Kljub impregnaciji z bakrovimi pripravki so delno strohneli že po petih letih. V primeru neustrezne zaščite je trajnost impregniranega lesa povsem primerljiva z nezaščitenim lesom. Vizualna analiza kolov je potrdila, da so bili razkrojeni z glivami rjave trohnobe. Iz trhlih kolov smo pripravili dve vrsti vzorcev. Prvi so bili za določanje vsebnosti bakra v lesu in drugi za določanje tlačne trdnosti. Vsebnost bakra v lesu smo analizirali z napravo Oxford instruments XRF analyser, tlačno trdnost pa z Univerzalnim testirnim strojem Zwick-Roell Z100. Prišli smo do spoznanja, da so bili koli slabo impregnirani in so vsebovali premalo bakra, zato so v kratkem obdobju izgubili veliko tlačne trdnosti.Importance of wood as building material is increasing. When we use it for construction purposes, we want to retain its mechanical properties as long as possible. Used outdoor, wood is exposed to wood deterioration agentsin ground contact its exposure is even more threatning. The researched wooden posts were applied in the ground at the playground in Ljubljana. Despite the fact that they were impregnated with a Cu preparation, they were completely degraded after 5 years. Their service life was thus comparable to service life of untreated wood. Wood posts were degraded by brown-rot fungi. 2 kinds of samples were prepared from investigated posts used for determination of Cu content and compressive strength. The results clearly show that wood posts were poorly impregnated. Mechanical properties degraded in quite short time