Properties of Laminated Strand Lumber Made with European Larch and Norway Spruce: A Preliminary Study

Abstract

This study investigated the feasibility of substituting Norway spruce (Picea abies) with European larch (Larix decidua) in structural applications, specifically in laminated strand lumber (LSL). Four types of experimental LSL panels were manufactured from these species. Two reference panels were produced exclusively from a single species: larch (LSL-L) and spruce (LSL-S). A third variant (LSL-L:S) consisted of a homogeneous mixture of 60% spruce and 40% larch strands. The fourth configuration (LSL-L:S:L) was designed as a mechanically differentiated three-layer structure, with larch strands in the surface layers. The mechanical and physical properties of the panels were evaluated by determining bending strength (MOR), modulus of elasticity (MOE), internal bond strength (IB), compression strength, water absorption (WA), and thickness swelling (TS). Statistically significant differences among panel types were identified for density and IB strength. The LSL-L:S:L configuration exhibited a significantly higher IB value (0.66 MPa) compared with the other variants. No statistically significant differences were observed in bending. Nevertheless, panels manufactured entirely from larch strands (LSL-L) and those containing 40% larch (LSL-L:S) demonstrated higher mean values than the spruce reference panels (LSL-S) in both bending and compression tests. Significant differences were also detected for WA and TS.