Bamboo is a natural bio-composite material that is both tough and possesses excellent mechanical properties. Its delicate structure and fiber arrangements play an important role in the mechanical properties and the fracture performance of bamboo. In this study, the fracture behaviors of bamboo due to tensile strength and bending were investigated using synchrotron radiation micro-computed tomography and environmental scanning electron microscopy (ESEM). Both tension and bending tests revealed that fibers are the key factors for bearing extra load and impeding crack propagation. Crack paths were found to be different in bamboo strips with different fiber percentages, and the interface between pulled-out fiber bundles and fiber break (in helix breaks and shearing break) was observed to be typical fracture characteristics in tension. Moreover, advanced micro-matrix cracking, interface debonding, fiber bundle bridging and the splitting of cell wall layers were found to be important fracture characteristics in bending. Both in tension and bending, a reasonably weak interface appeared to be beneficial for improving fracture toughness of fiber-reinforced bamboo. Thus, it is clear that “fiber bridging” mechanisms and “shear-lag theory” are well exhibited in bamboo.

To achieve value-added utilization of domestic bamboo and plantation wood resources, this study investigated the feasibility of using flattened bamboo and Chinese fir for manufacturing cross-laminated bamboo and timber (CLBT). Two types of adhesives, one-component polyurethane (PUR), and phenol resorcinol formaldehyde (PRF), and three applied pressure parameters (0.6, 0.8, and 1.0 MPa) were used to fabricate small CLBT panels (375 mm × 500 mm). In this study, block shear and delamination tests were conducted to examine the bond quality and durability of CLBT panels. The results showed that a significant difference in the bonding shear strength (BSS) in both directions. The bonding shear strength in the minor strength direction (BSS_minor) was 1.81–3.45 times higher than the bonding shear strength in the major strength direction (BSS_major). The adhesive type was the major factor affecting the bond quality and delamination, while the bonding pressure had no significant effect on the bond quality and delamination. Compared with PRF adhesives, CLBT specimens prepared from PUR had higher bonding shear strength (BSS) and wood failure percentage (WFP). However, the durability of delamination specimens prepared by PUR was not as good as layered specimens prepared by PRF.

Bamboo is a natural material widely used in buildings and bridges that has good mechanical properties. However, the longitudinal connection of bamboo culms is a major problem for the bamboo industry. In this study, sleeve-nailed bamboo specimens were produced, which contained three bamboo pieces. Two bamboo pieces with similar diameters were longitudinally joined by inserting a short bamboo culm with a smaller diameter, fixed with nails. The flexural performance of single beams and two-culm beams were studied. The load-displacement curves and fracture behavior of the specimens were investigated. The results show that the flexural bearing capacity of the single connected bamboo specimen was relatively smaller than that of an unconnected one, while the flexural bearing capacity of the two-culm beam was improved significantly. It can be seen that the lateral connection of bamboo specimens can improve the bearing capacity of the combined bamboo culms. This study provides a basis for promoting the application of sleeve-type nailed connections for bamboo.

As a natural biomass material, bamboo is subject to variations in culm size as well as in physical and mechanical properties that substantially influence processing and product quality. The diameter, thickness, and hardness of bamboo culms are critical factors for the output and quality of flattened bamboo board (FBB). In this study, the effects of different hardness modulus (HM) grades on the physical and mechanical properties of FBB were examined. The results showed that the HM of Moso bamboo (Phyllostachys pubescens) followed a normal distribution. Nine grades of HM could be divided by an interval of 5 KN/mm². The physical and mechanical properties of FBB were positively correlated with the HM of bamboo culms. Compressive strength, tensile strength, and shear strength, as well as the bending properties of FBB, each increased with increasing HM. Furthermore, under the same conditions, the mechanical properties of FBB were superior to those of both bamboo strips and bamboo culms. The softening, flattening, and planing processes were beneficial in improving the performance of bamboo. The strong correlation between HM and the properties of FBB indicates that the HM grading of bamboo culms can be used in bamboo processing to produce high-quality FBB products with uniform performance.