ABSTRACT

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.

摘要

Eucalyptus globulus和Eucalyptus nitens是澳大利亚最主要的硬木种植树种。尽管包含相当多的生长不规则性，但业界对从这些种植资源开发结构产品，尤其是交叉层压木材 (CLT) 的兴趣越来越大。在这项研究中，首次评估了由这两种材料制成的 CLT 的滚动剪切 (RS) 特性。使用聚氨酯粘合剂从每个物种制造两组高级和低级 CLT 面板。然后在三点弯曲试验下评估交叉层锯材密度和顶层和底层锯材的 MOE 对 CLT 的 RS 性能和失效模式的影响。两个物种标本的GA _{eff (LB)}和τ值。与低等级样品相比，这两个物种的高级样品显示出最高的剪切刚度和剪切强度值。此外，获得的 RS 值高于欧洲软木 CLT 标准中推荐的值。这些结果为从低等级人工林桉树木材中成功开发高价值 CLT 提供了有用的信息。