Rolling shear properties of cross-laminated timber made of fibre-managed plantation eucalyptus under short-span bending

Eucalyptus globulus and Eucalyptus nitens are the most dominant hardwood plantation species in Australia. Although containing a considerable amount of growth irregularities, there is an increasing interest by the industry in developing structural products, especially cross-laminated timber (CLT), from these plantation resources. In this study, for the first time, the rolling shear (RS) properties of CLT made of these two species were evaluated. Two groups of higher-grade and lower-grade CLT panels were fabricated from each species using polyurethane adhesive. The effects of the sawn-timber’ density in the cross-layer and the MOE of sawn timber in the top and bottom layers on the RS properties and failure modes of the CLT were then evaluated under three-point bending test. The results showed a positive correlation between the average MOE of the sawn timber in top and bottom layers and both GA_{eff (LB)} and τ value of the specimens from both species. The high-grade specimens from both species showed the highest shear stiffness and shear strength values compared to lower-grade ones. Furthermore, the RS values obtained were higher than those recommended in European standards for softwood CLT. These results provide useful information towards successful development of high-value CLT from the low-grade plantation eucalypts timber.