Experimental investigation into the mechanical properties of scrimber composite for structural applications

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Scrimber composite is a novel engineered wood-based construction material that is manufactured by reconstituting structural lumber using small-diameter tree species. In this study, clear specimens of the scrimber composite made from fast-growing poplar trees were tested to comprehend their mechanical properties; besides, a group of full-scale scrimber beams was tested to acquire the bending properties of structural-scale scrimber bending members. Then, comparison of mechanical properties was conducted among this scrimber composite, other common engineered wood, and bamboo scrimber. Finally, simplified longitudinal stress–strain models were proposed based on the experimental stress–strain relationships of the scrimber composite under the parallel-to-grain tension and parallel-to-grain compression scenarios. Results show that the scrimber composite can provide ideal mechanical properties, which are comparable or even superior to those of other common engineered wood/bamboo products. For the scrimber under the parallel-to-grain or perpendicular-to-grain compression, it is featured by ductile failure modes, such as crushing failure at the compressive zone and splitting failure with fractures propagating along the grain; whereas, for the scrimber composite under the shear, tension, and bending scenarios, it is featured by brittle failure modes, such as tension failure with flat fractures and shear failure along the bonding surface. Besides, it is proven that using the design strength of the clear specimens of the scrimber is reasonable and conservative for the design of structural-scale scrimber bending members. For the scrimber under the parallel-to-grain compression, the nonlinear characteristics of its stress–strain relationship can be described by one fourth-order polynomial function.