Research on shear mechanical properties of Eucalyptus scrimber and Ginkgo scrimber under different temperature conditions

In response to the intensification of global warming, the utilization of wood as a renewable resource in the construction sector has garnered widespread interest. Nevertheless, the efficient application of fast-growing timber is hindered due to its inherent drawbacks, including lower strength and susceptibility to decay. As an engineered wood composite, scrimber has emerged as a solution to significantly augment mechanical properties through structural reconstitution. This study investigated Eucalyptus scrimber (ES) and Ginkgo scrimber (GS) as the research subjects, comprehensively analyzing their failure modes, mass loss rate, load-displacement curves and shear strength under different temperatures. Shear tests and Scanning Electron Microscopy (SEM) were employed to elucidate the variation patterns of mechanical properties and microstructural responses across nine temperature gradients from −20 °C to 260 °C. The results demonstrate that the failure modes of scrimber can be divided into fiber shearing failure and fiber tearing failure; under relatively high temperatures, scrimber exhibits the adhesive failure. The mass loss of scrimber increases with rising temperature, and the variation of mass loss rate with temperature for ES and GS parallel to the grain under different temperature conditions can be predicted using a fitted model. Generally, shear strength shows a tendency to decrease with rising temperature across the entire gradient. Observations via SEM have revealed the microstructural characteristics associated with each failure mode, and have further clarified the influence of temperature on the shear strength of scrimber from a microscopic perspective. By improving the model used to predict that the shear strength of softwood under high temperatures follows a bilinear variation, the model is made to adapt with the material characteristics of scrimber. The Hyperbolic Tangent Model is applied to more accurately predict the changes in the shear properties of scrimber under different temperature conditions. This study establishes a correlation between microstructural damage evolution and macroscale mechanical degradation, providing essential empirical data and predictive models to guide the engineering design of scrimber in different temperature environments.