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.