Mechanical properties of sweet chestnut sawn wood and glulam performance

Abstract Sweet chestnut sawn wood is commonly found on ancient buildings across Europe. This is also evident in Portugal mainly in roof and floor structures. Knowledge about the mechanical properties of this species at that time was scarce, and it was primarily used due to its durability. If large section trees were available back then, this becomes a limitation nowadays. Engineered wood products (EWPs), such as glued laminated timber (glulam) help resolve this problem as thicker elements are used. Nevertheless, EWPs are usually made of softwoods, with standardization focused on these species. Current climate change poses challenges for industries that depend on nature, such as the timber industry. With the availability of softwood species affected, interest in hardwoods arose, and so has research. This paper focuses on experimentally characterizing chestnut sawn wood mechanical properties, such as modulus of elasticity (MOE) and strength of boards subjected to bending and tensile tests. Also, non-destructive characterization through the longitudinal vibration method (LVM) was performed. The average MOE from tension tests was about 13800 MPa, and 11100 MPa from the bending tests (24% lower than the former). The characteristic tensile strength value was 20.5 MPa, and the bending strength was 32.4 MPa. Although chestnut is a hardwood, concerning strength classes it is included in the softwood category, thus T20 and C30 strength classes for tension and bending, respectively, can be assigned. Strong correlations were found for the MOE based on the LVM. A preliminary campaign to evaluate the bending properties of glulam made from chestnut was conducted on ten specimens. A characteristic bending strength of 45.5 MPa was achieved. Good mechanical performance was observed, but enhancements are needed to ensure adequate bonding performance.