Effect of Post-harvest Storage on the Suitability of Acacia mangium for the Manufacture of Wood-wool Cement Boards

摘要

Acacia mangium wood has been found to be incompatible with cement and hence it is regarded as being unsuitable for the manufacture of wood-cement composites. The aim of this study was to determine whether manipulating the time that A. mangium billets are stored before processing could improve this species' suitability for the manufacture of wood-wool cement boards (WWCBs). Freshly felled A mangium logs were converted into billets 400 mm long (150 to 250 mm in diameter). Half of the billets were debarked and all billets were then stored outdoors for 0,6, 12 or 32 weeks. After storage, the billets were shredded and the cold water extractive content of the wood-wool was determined. Wood-wool cement boards were manufactured, and their mechanical properties were measured to assess the effects of storage time, soaking the wood-wool in water and using CaCl_2 as a cement setting accelerator. The cold water-soluble extractive content of A. mangium decreased continuously during storage. Boards made from unsoaked wood-wool obtained from fresh A. mangium billets had inferior board properties. Storage of billets for 6-12 weeks had a positive effect on the stiffness of boards but it was not as effective as water soaking at improving MOR. Billet storage and use of an accelerator improved board MOE and MOR particularly in boards made from unsoaked wood-wool. Storage of billets in the bark-free condition had a greater beneficial effect on the properties of WWCBs than storage of billets with their bark intact.