Manufacture of Low-cost Wood-Cement Composites in the Philippines Using Plantation-grown Australian Species: I. Eucalypts

摘要

Laboratory size (300 mm x 300 mm) wood-wool cement boards (WWCBs) with a thickness of 12 mm were produced using shredded wood ('excelsior') of Gmelina arborea, Eucalyptus tereticornis and E. grandis. The effects of soaking the excelsior in water prior to board production (0, 6, 12, 24 h), wood-cement ratio (50:50, 40:60, 30:70) and cement setting accelerator (none, CaCl_2, Al_2(SO_4)_3) on board properties were examined. The highest dry MOR values of the WWCBs were obtained from boards containing CaCl_2 as cement setting accelerator and at a wood-cement ratio of 40:60. Gmelina arborea excelsior required soaking for at least 6 h before it was suitable for the manufacture of WWCBs, but eucalypt excelsior could be used unsoaked. The MOE of the boards increased as the amount of cement increased, to a wood:cement ratio of 30:70, especially in the case of WWCBs made from G. arborea. Both the MOR and MOE of the boards dramatically decreased when boards were soaked in water for 24 h. In general, boards containing unsoaked excelsior exhibited the largest thickness swelling and water absorption irrespective of whether they contained a cement setting accelerator. The properties of certain boards containing eucalypt excelsior were comparable to those of boards made from G. arborea. This suggests that eucalypts may be used for the . commercial production of WWCBs, which could expand the raw material base for this panel product.