Mechanical properties of unidirectional strand board (USB): Effects of related EN standards and panel density

The demand for Engineered Wood Products (EWP), such as Cross Laminated Timber (CLT), is rising as it may have the potential to reduce the environmental impact of construction. However, these products exhibit low material yields and flexibility regarding wood species. Unidirectional Strand Board (USB), a high-yield, strand-based composite, presents an alternative intermediate with superior mechanical properties, greater versatility regarding species, and lower log quality requirements. Since different European standards are related to these materials, this study aims to evaluate the mechanical performance of pine-USB, with a focus on the influence of the EN testing standards. For this purpose, semi-industrial USB was produced at three density classes and the medium density (650 kg/m 3 ) was tested for bending, tension, and compression using EN 408 and EN 789 to compare the standards. Results showed that EN 408 is reliable for evaluating most stress states, except for flatwise bending. Based on that, all USB density classes were tested following EN 408, except for in-plane shear using EN 789, and were compared with OSB/4 and C24 strength-graded softwood. USB clearly surpassed OSB/4 requirements in parallel properties and outperformed most C24 strength requirements, although stiffness properties were lower for USB. Increasing density improved the mechanical properties disproportionately, with strong linear correlations observed for normal stress-related properties. USB exhibited high characteristic strength values, reduced variability, and high anisotropy, making it suitable for a strength-limited design of cross-laminated structures. These findings confirm USB’s potential as a sustainable, high-yield material as an intermediate for homogeneously built-up cross-laminated panels (CLP) or Hybrid-CLT, enabling more resource-efficient wood construction. • EN 408 reliably evaluated tension and compression properties of USB. • EN 408 showed 22 % higher parallel characteristic flatwise bending strength than EN 789. • USB (650 kg/m 3 ) surpassed OSB/4 and C24 in characteristic parallel strength values. • Normal-stress related mechanical properties of USB linearly correlated with density.