Three hardwoods technological properties characterization deteriorated by termites

ABSTRACT The objective of this study was to determine technological properties of Corymbia maculata. Eucalyptus dunnii and Eucalyptus saligna forest species, and to verify the changes in the characteristics of these Woods after food preference assay with Nasutitermes termites. The food preference assay was conducted through of the standard ASTM D 3345 (2008) adapted, evaluating the mass loss and mechanical properties at the end of the corresponding period. To obtain the results, the basic specific mass (μEB) was analyzed, with the aid of standard ASTM D 143 (2014), Janka hardness in the tangential and radial planes and the elasticity modulus (EC) and compression resistence (FC), both obtained by the compression parallel to grain test, before and after the termites attack. About the technological properties, it was verified that the Corymbia maculata species had the highest μEB (0.674 g/cm3) and mechanical resistance, with the highestvalues of Janka hardness in both anatomical planes (tangential = 664.6 kgf/cm2, radial = 593.8 kgf/cm2) and parameters related to compression parallel to grain (EC = 294.873 kgf/cm2, FC = 667.7 kgf/cm2). After the Nasutitermes termites test, the greatest mass loss was observed in the Eucalyptus dunnii species, thus indicating its food preference. These caused insignificant decreases in the mechanical properties, when compared to those measured before the food preference assay. From the results obtained, it is concluded that the wood deterioration by Nasutitermes, together with the anatomical characteristics, caused variations in the technological properties analyzed, however, the species Eucalyptus saligna and Corymbia maculata showed high natural resistance in relation to the termites.

摘要：本研究旨在测定斑皮桉（Corymbia maculata）、邓恩桉（Eucalyptus dunnii）与柳桉（Eucalyptus saligna）三种林木的工艺性能，并验证经鼻白蚁（Nasutitermes）取食偏好试验后，上述木材的特性变化。
取食偏好试验采用经改良的标准ASTM D 3345（2008）方法开展，于试验周期结束时评估木材的质量损失率与力学性能。
为获取试验数据，本研究依据ASTM D 143（2014）标准分析了基本体积密度（basic specific mass，缩写μEB），同时测定了弦向与径向的扬克硬度（Janka hardness），以及通过顺纹压缩试验得到的弹性模量（elasticity modulus，EC）与抗压强度（compression resistance，FC），上述指标均分别在白蚁侵染前后完成测定。
工艺性能分析结果表明，斑皮桉的基本体积密度最高（0.674 g/cm³），力学强度亦最优：其两个解剖方向的扬克硬度均为最高（弦向：664.6 kgf/cm²，径向：593.8 kgf/cm²），顺纹压缩相关参数也处于领先水平（弹性模量EC=294.873 kgf/cm²，抗压强度FC=667.7 kgf/cm²）。
经鼻白蚁取食试验后，邓恩桉的质量损失率最高，表明该树种为白蚁的偏好取食对象。与取食试验前的测定结果相比，白蚁侵染仅使木材力学性能出现小幅下降，且差异不显著。
综合试验结果可知，鼻白蚁引发的木材腐朽结合木材自身的解剖特性，会导致所分析的工艺性能发生一定变化；但柳桉与斑皮桉对鼻白蚁表现出较高的天然抗虫性。