The Mechanical Strength Properties, Treatability Retention and Hazard Classification of Treated Small-Clear Fast-Growing Acacia mangium Superbulk at Different Age Groups

Abstract

The slow growth rate of primer species has affected the supply available to accommodate the market demand. To overcome these problems, a study was carried out to fully utilise fast-growing timber as the primary resource to ensure the demand for timber logs continues. This paper aimed to determine mechanical strength properties, treatability retention, and hazard classification of 7-, 10- and 13-year-old small-clear samples of Acacia mangium superbulk collected from Daiken Plantation Sdn. Bhd. Bintulu, Sarawak, following treatment with 10% copper chrome arsenic. As a result of this study, the maximum strength was obtained from the 10-year-old age group, with the modulus of rupture (MOR), the modulus of elasticity (MOE), and compression parallel to the grain values of small-clear treated Acacia mangium superbulk reaching 118.76 N/mm2, 15,020 N/mm2, and 57.82 N/mm2, respectively. In addition, the treatability retentions obtained were 149.27 L/m3, 147.25 L/m3, and 141.09 L/m3, which were recorded from the 7-, 10-, and 13-year-old samples, respectively. Meanwhile, the dry-salt retentions obtained from the 7-, 10- and 13-year-old samples were 14.93 kg/m3, 14.73 kg/m3, and 14.11 kg/m3, respectively. Hence, this species is classified as moderately difficult to treat under CCA (treatability retention: 80–160 L/m3) and is categorised under the hazard class of H4 (dry salt retention: 12–16 kg/m3).