Effectiveness of Water Based Bentonite-Borate Slurry for In-situ Remedial Protection of Historic Wooden Piles: The Eurobor Protocol, Part 2

IRG/WP 11-30574

M. Theorin, K. Fimmerstad, K-M. Bandh

The study of the biocide product Eurobor®, water mixture of boric acid, borax and sodium bentonite, aimed to verify previous findings regarding borates penetration from a clay-water mixture of foundation timber. The product was applied on samples from 100 year old timber foundation from the city of Göteborg. Although in ground for this long the timber was in acceptable god condition due to ground water coverage of the foundation piles. The results show that borates diffuse readily into the sapwood and reach toxic concentrations (> 1 kg BAE/ m3 wood) for decay fungi in the decay front. Penetration of borates from the clay-mixture correlated with wood samples decay pattern and reached into sound heartwood. Concentrations reached 60000 mg BAE/kg in sapwood and 2500 mg BAE/kg inside the decay front towards heartwood. The technique with Eurobor® has been demonstrated both in field and laboratory to be effective by penetration and retention of the borates in toxic levels for decay fungi.

Keywords: Eurobor, borates, timber piles, wooden grillages, bentonite, foundation, clay

Conference: 11-05-08/12 Queenstown, New Zealand

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