Strength properties of preservative treated pine and spruce wood after super-heated steaming
Possible changes of strength properties of CCF pressure impregnated pine and spruce with subsequent steaming at 110°C respective 120°C for 30 min were examined. For spruce analysis of variance indicated that none of the processes had a significant effect on bending strength, compression strength and the corresponding modulus of elasticity as well as on impact bending strength and shear strength radial resp. tangential to the grain. For pine no changes in the bending strength and the compression strength could be detected. The impact bending strength of unsteamed or steamed impregnated samples decreased with 12% compared to non-treated controls due to the brittleness of the salt-impregnated timber. It could be proved that neither steam treatment of 110°C nor of 120°C for 30 min. alone causes a significant change of strength properties of pine and spruce. Arising variations can be explained from anatomical wood properties as well as salt deposits in the samples as a consequence to impregnation.