Alik Duju & Takashi Nakai
Mechanical properties of Acacia mangium planted in Sarawak, Malaysia
Ten trees of 13-year old Acacia mangium were sampled and fifty-four small clear
specimens were tested. The British Standard (BS 373.1957) method on testing small
clear specimens of timber was adopted to obtain the strength properties of the species.
It was found that the mean values of modulus of rupture, modulus of elasticity and
compressive strength tested at green condition were 86.4 MPa, 10.9 GPa and 36.8 MPa
respectively. The average moisture content was 114 % and their basic density was
0.51 g/cm3. Based on their compressive strength, the timber was classified under
Strength Group C by Burgess's grouping. It was revealed that the strength properties
and basic density were higher at outer portion compared to the inner portion of the wood.
Andrew Tukau Salang and Tomoyuki Fujii
Physical and Anatomical Characteristics of Acacia mangium Willd planted in
Sarawak, Malaysia
The average thickness of the sapwood is 11 mm, whitish in colour and the heartwood
is slightly pale brownish to purplish brown. The timber is slightly interlocked with
smooth and even texture. It is a strong timber with an average oven-dried density of
471 kg/m3, that it is suitable for interior structural timber and furniture. The density
variation amongst trees is about 11%. The density increases from the pith towards the
heartwood and decreases at the sapwood. Mostly solitary vessels, multiple vessels are
also common especially radial multiple of 2, medium size, moderately numerous, evenly
distributed, deposit and tyloses present. Vessel diameter also increases from the pith
towards the sapwood. Vessel element length is short and it increases in length from
pith towards the heartwood and slightly decreasing at the sapwood. The wood fibre is
small with very thin wall and long that it is suitable for pulp and papermaking. The
fibre diameter is larger with higher variation at the pith compared to the heartwood
and sapwood, which is almost similar in size. Fiber wall thickness showed slight
increases from the pith towards heartwood and sapwood. Fibre length variation is
also higher at the pith compared to the heartwood and sapwood that showed almost
similar in length. Fibre length also increases from the pith towards the heartwood
and slight decrease at sapwood. The variation in the parameters of the vessels and
fibres are found to be higher at the pith compared to the heartwood and sapwood.
The variation in the characteristics of vessel and fibre is higher within trees
compared to between tree in Acacia mangium. The core wood that includes the pith
consisted of juvenile wood is about 10%, and utilisable wood that consists of
heartwood and sapwood is 90%.