Encapsulation of poles to prevent moisture uptake – a laboratory test

IRG/WP 16-40753

K-C Mahnert, U Hundhausen

Premature failure of utility poles due to decay in soil contact is the main reason for early removal of utility poles, a measure that implies extra costs for utilities. Remedial treatments and barriers are common methods to prolong the service life of utility poles. The first part of this paper gives an overview of mode of action and commercial application of barrier systems as described in the literature. The second part of the paper summarizes a research project conducted at the Norwegian Institute of Wood Technology. In this project, the practicability of encapsulating wooden poles by extrusion of WPC or HDPE onto the pole was proven. The water tightness of these barriers and the suitability of conventional bolting methods applied to encapsulated poles was evaluated in a laboratory test. In the course of the 3-step test, sections of the encapsulated poles were exposed to high and low temperatures (65 and -25 ºC) and liquid water. An influence of the harsh temperature changes on the water uptake of the poles during the 3-step test was not observed. The barriers not damaged by bolting showed sufficient protection against water uptake. Water ingress into bolted pole sections exposed to water, however, resulted in moisture contents in the poles above 25 %. Bolting of the pole sections with the help of an MS-polymer showed improved water tightness.

Keywords: utility pole, barrier, encapsulation, laboratory trial, WPC, HDPE, water uptake, service life

Conference: 16-05-15/19 Lisbon, Portugal

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