Chemistry Preservation with CCB of Timber Fence Posts by Sap Displacement Methods

Abstract

Timber from eucalyptus and pines trees used in contact with the ground requires preservative treatment to prolong their useful life under natural condition. To obtain resistant timber fence posts to xylophagous attack, this research aimed to evaluate the preservative treatment with CCB applied in Eucalyptus dunnii Maiden and Pinus taeda L woods by sap substitution method. We found that Eucalyptus and pine treated posts had equilibrium moisture content of 17.33% ± 0.51 and 17.02% ± 0.27, respectively. The equilibrium moisture content was 10% higher for eucalyptus and 5 % higher for pine than that for untreated fence post. The mean basic density was 438 kg/m³ ± 21 and 395 kg/m³ ± 23 respectively, and the porosity of both woods was about 59%. Eucalyptus and pine wood presented high porosity and low density, which may promote a good impregnation of CCB preservative. The mean active ingredients of treated fence posts were 6.18 kg i.a/m 3 ± 0.41 for eucalyptus and 5.88 kg i.a/m 3 ± 0.73 for pine. Finally, the treated fence posts had a low cost. The average cost of treatment for eucalyptus and pine was US$ 1.55 per meter ± 0.14 and US$ 1.63 per meter ± 0.07, respectively. This price can be even lower if the owners had the wood in their properties. In conclusion, the treatment reached the minimum requirement of 5 kg of active ingredient per cubic meter of treated timber with a low cost, being the fence post apt to be used directly in contact with the ground.