MATERIAL AND METHOD 1 Materials
Bogor, 21-22 October 2015
417 As we all know that the demand of wood as furniture and building materials always increase in
line with the increase in the number of population. The exsisting wood supply for furniture and building materials is not able to fulfill the demand. Therefore the search for solid wood
substitutes is urgent concern. Although there is a long history to use bamboo as construction materials, furniture, household utensils and handicrafts in Indonesian villages, the shape and
dimension appear to limit the usage of bamboo as wood substitute. Due to its circular and hollow shape, bamboo must be converted into the flat and relatively thick materials as solid
wood substitutes. Producing bamboo composites is one way to overcome the limitation. Nowadays it is fortunately possible to produce timber-like-materials with the desired
dimensions from bamboo strips, so-called laminated bamboo lumber LBL by the aid of appropriate adhesives. LBL a certain type of bamboo composites is a lumber-like product in
dimensions, consisting of several layers of bamboo sheets bonded together with the grain in parallel direction, and may be formed into planks or beams depending on the thickness, width
and length of the products. Studies on the development of LBL made from bamboo strips as a potential solid wood substitute have been carried out by previous investigators Lee and Liu,
2003; Sulastiningsih et al., 2005; Guo, 2007; Rittironk and Elnieiri, 2008; Correal and Lopez, 2008; Sulastiningsih and Nurwati, 2009; Correal and Ramirez, 2010; Mahdavi et al., 2011;
Sulastiningsih et al., 2012; 2013b; 2014. The processing parameters, however, applied in those studies were different with in this study. This paper describes the results of an experiment to
determine the effects of varying pressing time and pre-treatment of bamboo strips on the properties of LBL made of G. robusta glued with isocyanate adhesive.
2. MATERIAL AND METHOD 2.1 Materials
Twenty mature culms of mayan bamboo Gigantochloa robusta were collected from private gardens in Sukabumi, West Java. The culms used in the experiment were obtained by taking
out the first segment at ± 50 cm in length from the bottom to remove the irregular or defect part of the bamboo culms. The remaining culms only the bottom and middle parts
measuring about 8 m in length were cross cut into segments. Each segment was 125 cm in length and generally had two internodes. The average diameter and wall thickness of segments
of G. robusta were 10.32 cm and 1.25 cm respectively. Boron solution and H
2
O
2
solution were used as preservative and bleaching treatment respectively. Water base polymer-isocyanate was
used as adhesive. 2.2 Preparation of Bamboo Strips
Each bamboo segment 125 cm in length was manually fed into a bamboo splitter machine. Seven to nine strips were obtained from each segment, each about 2 cm wide. Only straight
bamboo strips were used for this study. After scraping out the inner and outer layers, the selected strips were then planed and stacked for air drying at room temperature for one week.
The bamboo strips were then assigned into 3 groups by pre-treatment methods: untreated, cold soaking in 7 boron solution for 2 hours, and bleached by 15 hydrogen peroxide
solution. After pre-treatment, the bamboo strips were then sun-dried to about 12 moisture content and then were cross cut into 60 cm length. The bamboo strips were then further dried
in the oven at 50ºC for 24 hours to obtain ± 10 moisture content. 2.3 Producing Bamboo Sheet
Each bamboo sheet comprised eight bamboo strips. The bamboo strips were assembled side- by-side and edge-glued using isocyanate adhesive water based polymer-isocyanate. The glue
mix main fluid 100 and cross linker 15 of 250 gm
2
for a single glue line was then hand-
Bogor, 21-22 October 2015
418 spread on each side surface of bamboo strips using a metal spatula. The assemblies were cold-
pressed for 45 minutes and one hour using a wooden clamp. 2.4 Producing Laminated Bamboo Lumbers LBLs
LBLs were produced by assembling three layers of bamboo sheet with the grain in parallel direction. The glue mix main fluid 100 and cross linker 15 of 250 gm
2
for a single glue line was then hand-spread on each side surface of bamboo sheet using a metal spatula. The
assemblies were cold-pressed for 45 minutes and one hour using a wooden clamp. Four replications for each treatment combination of LBL were prepared. The LBLs produced were
conditioned for two weeks before testing. 2.5 Testing
The laminated bamboo lumbers were cut into desired specimen dimensions and measured for density, moisture content, thickness swelling, width expansion, modulus of rupture MOR,
modulus of elasticity MOE, compression strength and bonding strength. The tests were performed using the American Standard ASTM D 1037-93 ASTM 1995 with some
modifications and Japanese Standard for Glued Laminated Timber JPIC 2003 for evaluating properties of LBLs. A completely randomized design with factorial experiment was used with
pressing time and pre-treatment method of bamboo strips as the treatment factors. Four replications were prepared for each treatment combination.