Effect of treatment time on creosote penetration and retention in eucalyptus tree species transmission poles

Abstract

Utility poles from different materials ranging from wood, metal and concrete have been widely used in the transmission and distribution of electricity for decades. The commonly used poles in Uganda are from Eucalyptus however, they consist of cellulose, hemicellulose and lignin making them susceptible to biological attack from termites and, fungi. The biological attack changes the technological properties of the wood such as chemical, physical and mechanical properties that may bring about early failure of poles. To extend the service life of these utility poles, they have been impregnated with preservatives such as creosote using pressure treatment process in varying time intervals. The main objective of the study was to assess the relationship between treatment time and creosote penetration and retention in Eucalyptus transmission poles. Treatment was done using full cell pressure treatment process using initial vacuum time of 15 minutes and 20 minutes and pressure treatment time of 85-130 minutes as pressure time A and 140-280 minutes as pressure time B were used to study 5 pole samples per charge to determine penetration and retention of creosote reservative for 310 Eucalyptus transmission poles with a recommended moisture content between 25-30% below FSP in 62 different charges. Results obtained showed that penetration and retention of creosote preservative into the transmission poles were highest in 20 minutes initial vacuum time treatment and were also highest in 280 minutes pressure treatment time. The results further showed that there was a high positive Pearson correlation coefficient (0.788) between penetration and retention of creosote preservative. It can be concluded that treatment time both initial vacuum time and pressure treatment time are very important since they can highly determine the amount of creosote preservative in transmission poles. Therefore, care should be taken to use the right treatment time while treating utility poles. However, it is recommended that more research on the effect of creosote treatment time on the mechanical properties of Eucalyptus transmission poles since treating wood for a long time under pressure may weaken it in return.