A field study on the suitability of the European lap-joint test
M Grinda, Ö Bergman, H-V Borck, D Dickinson, P Esser, R Gründlinger, H Leithoff, S Molnar, L Paajanen, N Pfabigan, E D Suttie, F Thomassin, T Nilsson, J Van Acker, M Van Der Zee, A Voss
Within the framework of the European SM&T Research Project "Co-normative research on field tests for wood preservatives out of ground contact in conjunction with methods for preconditioning test specimens prior to test" (FACT) one aim was to establish the suitability of the European lap-joint test (as it is described in ENV 12037:1996) to assess wood preservatives in the field in EHC 3. Scots pine and/or spruce lap-joints treated by penetrating and/or superficial processes with three types of model preservatives were exposed at seven northern European test fields and one test field at Guadeloupe. The course of decay by wood destroying fungi and discoloration by stain fungi was assessed semi-annually over a period of now three years. The results show that the European lap-joint as such - which is smaller in size than the American lap-joint - is applicable both for testing the preventive efficacy of wood preservatives against decay fungi and against stain fungi. But depending on the local climates the method can be very time-consuming. Whereas discoloration of untreated lap-joints occurred within six month of exposure at all test sites, decay in untreated specimens was observed after six months at Guadeloupe, after one year near Paris but not within three years of exposure at Uppsala. Treated lap-joints showed early decay at Guadeloupe and relatively early decay near Paris but none or negligible decay at the other exposure sites. The rating scheme of ENV 12037 needs to be amended as to meet more specifically the patterns of discoloration and decay in practice.
Keywords: LAP-JOINT; TEST FIELD; TEST METHOD; ABOVE GROUND TESTING; ASSESSMENT; RATING SCHEME; CLIMATE