Treatability of beechwood railway sleepers with potential creosote substitutes
N Pfabigan, E Habla, R Gründlinger
Maintenance of an efficient railway infrastructure still requires the use of wooden railway sleepers, particularly because wooden sleepers have more favourable properties for intensified vibrations than concrete or steel sleepers. Creosote, used for decades for the impregnation of railway sleepers, will possibly no longer be available for this application due to European legislation. This reveals the necessity for potential substitutes for creosote. Lab trials, performed in former investigations, proofed the potential of copper amine-based wood preservatives in this field of application. However, so far copper-amine based wood preservatives are mainly used for the impregnation of softwoods and little knowledge is available about impregnation of the hardwood species beech.
The tests reported here outline the treatability of beechwood railway sleepers with two copper-based wood preservatives with regard to preservative penetration, retention and distribution. For this purpose beechwood railway sleepers were impregnated with two copper-amine based wood preservatives by vacuum-pressure treatment. Chemical analyses of copper, as distinct active ingredient, revealed an adequate uptake of preservative and a sufficient distribution in longitudinal and transverse direction for both wood preservatives. A slight gradient of preservative retention was detected, with higher retentions in the parts close to the end-grain and slightly lower ones in the middle of the sleeper. Higher preservative uptake was also noticed in the outside margin compared to the inner part of sleepers. However, in all cases, the required minimum uptake of preservative was achieved or, respectively, in most cases, exceeded.