Evaluation of the Mechanical Properties of Pine, Larch, and Spruce Wood Subjected to Saline Treatment

Structures made of wood are used extensively in applications that require mechanical reliability under variable environmental conditions. Several softwood species were investigated, including pine (<i>Pinus sylvestris</i> L.), spruce (<i>Picea abies</i>), and larch (<i>Larix decidua</i>). This study investigated the tensile deformation behavior of each species with a special focus on the mechanical energy demand of the tensile process. Samples were conditioned in an aqueous saline medium for defined exposure periods and compared with controls. The energy of deformation was determined from stress-strain relationships of tensile tests under identical loading conditions. Results indicate that saline conditioning alters the tensile response of the examined wood species in a species-dependent way. Tensile strength increased in pine wood after exposure, whereas spruce and larch showed different trends depending on conditioning duration. A wide range of tensile strengths was recorded for all samples, ranging from 5.4 MPa to 102.0 MPa. Controlled saline exposure significantly influences the mechanical behavior of softwood species, as indicated by the findings. Evaluating wood performance under modified environmental conditions, both deformation energy and strength parameters should be considered. The main novelty of this study is the introduction of an energy-based description of tensile deformation, in which the total tensile work is calculated from force-displacement relationships, enabling differentiation of specimens with similar tensile strengths but fundamentally different deformation and failure properties. A practical advantage of the proposed energy-based approach is that it provides additional insight into the deformation tolerance and failure behavior of saline-conditioned wood, thus enabling a more reliable assessment of material performance under unpredictable environmental conditions.