Microwave modification, preservative treatment and industrial tests of Radiata pine railway sleepers

The use of hardwood railway sleepers in Australia is limited by hardwood timber resources. Softwood sleepers made from plantation Radiata pine (Pinus radiata) may replace them. Low permeability of pine heartwood does not allow to impregnate them well with preservatives. Microwave (MW) wood modification increases heartwood permeability and improves preservative distribution and uptake. The experimental study of MW sleeper modification and impregnation allowed the rational MW process parameters and preservative treatment schedules to be determined, with an estimate of the effect of MW treatment on sleeper quality. Tests of MW modified and impregnated with Copper Naphthenate oil preservative sleepers in a railway track allowed to assess sleeper conditions after 3.5 years of service and provide recommendations to the industry. The costs of MW sleeper processing are acceptable to industry and provide good opportunities for commercialization.