Effects of density on the penetration and retention of creosote in transmission poles in Uganda
Abstract
Majority of utility poles used in Uganda are of eucalyptus species and are usually treated with
coal tar creosote. However, frequent premature failures of treated poles in service have been
reported in different parts of the country. This might be attributed to the wood materials,
suitability of the preservative chemicals and the methods of treatment. The main objective of the
study was to determine the effects of density on the penetration and retention of creosote in
transmission poles. Thirty defect free and air-dried poles having an average moisture content
below 28% and 14m long were randomly selected for the study. Specimens were treated with
creosote using the vacuum/pressure process. Density of the specimens and their corresponding
creosote penetration and retention were determined. There was a significant difference (p=0.000)
between creosote penetration and the minimum penetration requirement (15mm) and there was
also a significant difference (p=0.000) between creosote retention and minimum retention
requirement (115kg/m3
). A negative correlation was observed between; creosote penetration and
wood density, and creosote retention and wood density. A positive correlation was observed
between penetration and retention. The schedule of pole treatment should be varied with pole
density where poles with high density are treated for longer periods of time in order to obtain
higher creosote penetration and retention.