Thermal decontamination of railway sleepers for recycling. Changes in mechanical wood properties

Old creosote-treated sleepers are considered as a problematic waste and their use is strictly regulated. It has been shown that decontamination by a conduction thermal treatment up to 220°C under vacuum conditions and longer than 20 hours allows a significant PAHs removal from the wood tissue. After decontamination the sleepers could be re-used in a solid form with a low impact on the environment. In order to evaluate the possible applications of decontaminated wood railway sleepers, their mechanical properties were investigated before and after decontamination by non-destructive tests with ultrasonic wave's propagation and penetration resistance methods. From the results achieved, the process does hardly damage the material and must be improved to allow structural utilisations with decontaminated railway sleepers.