Protective Levels of Borates in timber Foundation Piles 5 – 18 Years after In-situ Remedial Treatment in Areas with Wet Clay Ground Conditions. The Jerbor and Eurobor Protocol, Part 1.
M Theorin, K-M Bandh
Timber has been used as foundation piles and grillages for decades or even centuries. Since the late 1970s a method for investigate, analyze and treat building timber foundations in soft clay grounds against decay fungus with a biocide have been developed and used by the late professor Allan Jerbo. Settling of buildings in soft clay grounds is continuously monitored and if damages to the building occur as a consequence of differential settling actions must be taken. Settling pattern, ground geotechnical properties and the condition of its timber foundation is evaluated. Settling damage is due to decay of foundation timber have been treated with biocides and special application techniques and results from 5 - 18 years after using these techniques, The Jerbor or Eurobor protocols, show that in-situ treatment with a water solution of borates have been successful. Samples of wood from piles were taken by digging or coring below the building foundations and determination of total boron in wood samples show concentrations in the decay front well above the 1 kg BAE /m3 wood limit for preventing wood degradation by fungi. One example of Jerbor® showed 1.74 kg BAE/m3 wood in average 18 years post treatment simultaneous as the foundation groundwater concentrations was 96 mg BAE/liter in average. To great damage of foundations cannot be repaired and consequently a new steel and concrete foundation have to be made. Costs are often in the 0.5 – 10 million € range for this work why a building benefit from choosing a preservative treatment when this is possible. Approximately 200 foundations have been treated with the Jerbor and Eurobor technique.