Performance trials of treated hardwood fences

IRG/WP 02-30281

L J Cookson D Scown, B Iskra

This paper examines the performance of the traditional hardwood paling fence used in Australia, after preservative treatment. Unseasoned rails, palings and plinths of the low natural durability species Eucalyptus regnans (mountain ash) and E. obliqua (messmate) were treated with PEC (pigment emulsified creosote) or PROCCA (an oil emulsion of CCA). Treated posts of these species were also compared with a naturally durable species used for posts, E. camaldulensis (river red gum). As the sawn timbers were mostly heartwood, penetration depths achieved were generally poor. The effect of incising posts, and notching or cutting timbers before and after treatment were examined, along with alternative construction methods. Performance was compared in laboratory ‘agar trays’, an Accelerated Field Simulator, and the field, enabling correlation between the various test methods. Results, including five year field inspections, showed that the above ground portions of the fence were still sound, compared to an untreated model fence. PEC provided better protection than PROCCA to timbers cut after treatment, due to its ability to bleed across cut surfaces. After five years, PEC treated posts performed as well as untreated E. camaldulensis posts.

Keywords: Fence, Eucalypt, PEC, PROCCA, Accelerated Field Simulator, Field test, E. regnans, E. obliqua, E. camaldulensis, Incising, Retention

Conference: 02-05-12/17 Cardiff, Wales, UK

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