Standard and accelerated testing of boron-additive wood protection systems

IRG/WP 05-30381

A Mohareb, J Van Acker, M Stevens

The main objective of this research was to determine the effectiveness of boron-additive protection systems for above ground applications by means of field testing. The two field test procedures used are based on the L-joint test described in the European standard EN 330. For the first set up the boron treated timber was coated in accordance with the standard EN 330 system. The second set up is based on an accelerated test simulating uncoated applications and includes an additional moistening of the jointing area. After three years of aboveground exposure, boron preservatives are still providing an adequate protection to coated L-joint specimens. Based on the results obtained it can be concluded that boron-based compounds still provide good protection after three years of natural weathering when protected by a three-coat finish. Similar uncoated L-joints treated the same way show rapid deterioration under the accelerated exposure conditions applied. The mass loss data revealed a significant level of decay for the uncoated specimens even when treated with boron-additive formulations. This is attributed to the high leaching hazard related to the accelerated exposure method used. The latter proves to be too aggressive for all tested boron-based preservatives when unprotected by surface coatings. A treatment with 1 % CCA under the same conditions was still performing adequately after 3 years even under accelerated L-joint exposure of uncoated test samples.


Keywords: Scots pine, boron, additives, L-joint, accelerated testing

Conference: 05-04-24/28 Bangalore, India


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