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With bamboo’s rapid renewability, short rotation period, versatility, and good mechanical properties, engineered bamboo composites have undergone significant evolution. This paper examines the recent changes in bamboo product manufacturing, starting with a wholistic classification of culm breakdown to the plethora of different constituent elements: full culm, flattened bamboo, bamboo bundles, splits/strips, mats/curtains, and strands. Highly cracked flattened strips used in bamboo scrimber are 4–5 times greater in specific surface area than crack-free strips, requiring an estimated 6–10 times higher resin consumption than laminated bamboo. Based on their structure, bamboo composites can be classified into three categories: 1) lamination of minimally modified culms, 2) laminated mat structures with controlled or semi-random placement of constituent elements and 3) random mat structures composed of thin bamboo strands. Composite formation is transitioning from random placement of large, thick strips to more controlled layup with secondary elements of stitched strip curtains, helping minimize edge-to-edge strip overlaps and improve bonding efficiency with less mat compaction. Density-structure-strength property relationships are also compared between various engineered bamboo and common engineered wood products. Other technical advancements include crack-free flattened bamboo and hybrid bamboo-wood products.

Reducing the destruction of bamboo's original structure to produce high-utilization and high-performance engineered bamboo products has long been a goal in the industry. This study developed a new natural arc-shaped laminated bamboo-wood lumber (NALBWL) based on the natural structure and original form of bamboo, using equal arc-shaped bamboo split (EASB) and poplar veneer. A multi-scale analysis of the bending performance and crack propagation dynamics of EASB and NALBWL was conducted. EASB's modulus of elasticity (MOE) and rupture (MOR) were 1.06 and 1.17 times higher than those of air-dried bamboo, respectively, exhibiting excellent mechanical properties. Additionally, its toughness in the full and elastic-plastic stages were 1.24 and 1.38 times higher than those of air-dried bamboo. NALBWL's MOE and MOR were 12.73 GPa and 174.41 MPa, fully meeting structural material requirements and even surpassing most engineered bamboo products. Moreover, NALBWL's radial bending load values were 2.29 and 2.24 times higher than that of EASB and air-dried bamboo, respectively, and it also demonstrated excellent water heat and drying resistance in impregnation and peeling performance. Real-time crack propagation analysis indicated that NALBWL's superior mechanical properties benefited from the respective advantages of bamboo and poplar veneer. This work showcased the application of "natural form-inspired design" in developing bamboo-wood composite materials, and the conclusion provided a reference for the sustainable development of engineered bamboo products and the study of biomass material fracture mechanisms. • The equal arc-shaped bamboo split exhibits exceptional mechanical properties, maintaining its natural structural integrity. • A high-performance natural arc-shaped laminated bamboo-wood lumber was manufactured. • The tree-ring-like bionic structure inhibits crack propagation of the bamboo-wood composites. • This new composites can meet the stringent performance requirements for high-grade building structural materials. [ABSTRACT FROM AUTHOR]

Controlling the variability in mat structure and properties in bamboo scrimber (BS) is key to producing the product for structural applications, and wide strip scrimber (WBS) is an effective approach. In this study, the effects of scrimmed bamboo bundle morphology and product density on the properties of WBS were investigated. WBS panels were manufactured and tested using wide (200 to 250 mm) bamboo strips with different fiberization intensity. Maximum strength properties (flexural, compressive, and shear strength), and lowest thickness swelling and water absorption were achieved with three or four passes due to the higher resin absorption by strips. For balanced product cost and performance, we recommend 1–2 fiberization passes and a panel density of 0.9–1.0 g/cm3. Panel mechanical properties were compared with other common bamboo composites. Bamboo scrimber products were highly variable in properties due to differing manufacturing processes, element treatments, and suboptimal mat structure. Products including laminated bamboo lumber and flattened bamboo made from nonfiberized elements show markedly different relationships between strength and elastic properties mostly due to inadequate bonding between the laminae, which causes premature bond-line failure. This study helped improve the understanding of the structure–property relationship of engineered bamboo products while providing insights into process optimization. [ABSTRACT FROM AUTHOR]

Controlling the variability in mat structure and properties in bamboo scrimber (BS) is key to producing the product for structural applications, and wide strip scrimber (WBS) is an effective approach. In this study, the effects of scrimmed bamboo bundle morphology and product density on the properties of WBS were investigated. WBS panels were manufactured and tested using wide (200 to 250 mm) bamboo strips with different fiberization intensity. Maximum strength properties (flexural, compressive, and shear strength), and lowest thickness swelling and water absorption were achieved with three or four passes due to the higher resin absorption by strips. For balanced product cost and performance, we recommend 1–2 fiberization passes and a panel density of 0.9–1.0 g/cm3. Panel mechanical properties were compared with other common bamboo composites. Bamboo scrimber products were highly variable in properties due to differing manufacturing processes, element treatments, and suboptimal mat structure. Products including laminated bamboo lumber and flattened bamboo made from nonfiberized elements show markedly different relationships between strength and elastic properties mostly due to inadequate bonding between the laminae, which causes premature bond-line failure. This study helped improve the understanding of the structure–property relationship of engineered bamboo products while providing insights into process optimization.

Bamboo units used for manufacturing engineered bamboo products are typically processed by breaking and planing, resulting in products with high glue content, substantial costs, and adverse environmental impacts. To address these issues, a simple and effective approach for processing standard bamboo units, based on the natural form and structure of bamboo, is proposed and tested in this study. More specifically, bamboo splits were dried at 0.05 MPa pressure and 140 °C for about 2.5 h in a pressurizing device. After drying, the bamboo splits each formed an equal-arc shaped bamboo split (EASB) in which the inner and outer radii were roughly equal. The EASB unit represents a double breakthrough of a high material utilization rate (as high as 80%) and low damage to bamboo. Additionally, the appropriate drying technique improves the dimensional stability and retains the excellent mechanical properties of natural bamboo. This work demonstrates the concept of "natural form inspired design," and the EASB provides a basis for wider applications of sustainable engineered bamboo products. [Display omitted] • An integrated process of bamboo split radian adjustment and drying is presented. • The bamboo unit developed herein retains bamboo's natural structure and texture. • The bamboo utilization rate of this bamboo unit is as high as 80%. • The bamboo unit retains the excellent mechanical properties of bamboo. [ABSTRACT FROM AUTHOR]