Post-consumer wood properties as an important factor in the quality of constructional materials

Abstract

An additional and underutilized resource that accumulates annually is post-consumer wood. The annual potential volume of this resource of wood raw material in Ukraine is about 2.0 million tons. This important source of wood raw materials, due to the lack of a regulatory framework, scientific and technical foundations for use, classification, technological developments and practical recommendations, has not yet received proper use at woodworking enterprises in Ukraine. We have made the first attempts to study the physical and mechanical properties of the post-consumer wood and suggest ways to use it. Among a variety of indicators of the mechanical and physical characteristics of used wood specimens from roof structures, we have identified the most important ones that are important for the use of such wood in the manufacture of panel structural materials, in particular in the production of blockboards. It is substantiated that the identification of the main indicators of post-consumer wood (PCW), and their comparison with the same indicators of primary wood (PW), in particular, the main softwood species, is an urgent scientific problem, since provisioning the regulatory database will ensure the manufacture of high-quality wood products with maximum consideration of the mechanical and physical characteristics of this potential reserve of raw materials, which is advisable to use in woodworking technologies for the production of structural materials and components of furniture products. Physico-mechanical parameters of PW and PCW of pine, spruce, fir and larch were identified and it was found that with time of operation under different conditions they change, mainly towards decreasing their values: density – by 1.54-4.67%; impact hardness – by 1.37-4.11%; static hardness – by 0.72-7.11%; cross-breaking strength – by 5.94-8.33%, shearing strength – by 3.08-7.23%; compressive strength along the fibers – by 1.72-8.89%. The main causes of age-related changes in the properties of PCW are due to the following factors: biological – partial internal rot, weathering, insect damage; mechanical – scratches, shearing, small holes from fasteners and other defects from use; operational – the influence of dynamic and power loads, surface finishes and other factors on structural elements of wood products. Possessing the obtained indicators and knowing the change in the physical and mechanical properties of PCW with age, we can recommend this additional wood material for the manufacture of structural materials: with mechanical damage visible on the surface and color changes – for the manufacture of blockboards; with high-quality surfaces - for the manufacture of furniture panels The results of studying the indicators of the physical and mechanical properties of PCW of the main softwood species made it possible to understand the nature of the change in these indicators in comparison with PW, to elaborate practical recommendations for efficient material processing, and to fill the regulatory database.

Keywords

• woodworking technologies
• physical and mechanical properties
• strength
• density
• hardness
• processing
• wood resource