Physical and Mechanical Properties of Four Varieties of Ironwood Bambang Irawan* Faculty of Foretsry, Jambi University Jl. Lintas Jambi - Muara Bulian Km. 15, Jambi 36122 *Corresponding author: [email protected] Abstract Bulian or ironwood (Eusideroxylon zwageri Teijsm. & Binn.) belongs to the family of Lauraceae. The most valuable characteristic of ironwood is very durable and an excellent physical and mechanical properties. Four varieties of ironwood namely exilis, grandis, ovoidus and zwageri had been identified based on morphological characteristics and genetic marker. It has never been determined that there is a correlation between mechanical properties of wood and the varieties. Four logs samples were collected from Senami forest, Jambi, Indonesia. The Physical and mechanical property test was referred to British Standard (BS) 375-57, including moisture content, density, shrinkage, bending strength. Some parameters of physical and mechanical properties were not significantly different among investigated logs. These were dry air moisture content, tangential shrinkage green to oven dry, green hardness and green compression parallel to grain. Other parameters were significantly different among investigated logs. The cluster analysis based on physical and mechanical properties shows that zwageri and ovoidus formed one cluster with a higher degree of similarity than another cluster, which was formed by grandis and exilis. This dendrogram is synchronized with the dendrogram which was formed based on other morphological structures of ironwood. Keywords: ironwood, physical and mechanical properties, senami forest, varieties Introduction first noted in 1955. Population reduction Bulian or ironwood (Eusideroxylon caused by overexploitation and shifting zwageri Teijsm. & Binn.), synonymous agriculture has been noted in the with Bihania borneensis Meissner and following regions: Kalimantan, Sumatra, Eusideroxylon lauriflora Auct., belongs Sabah, Sarawak and the Philippines. Its to the family of Lauraceae, tribus of regeneration in logged forests is limited. So far, the species has only been planted Cryptocaryeae and subtribus of on a small scale because the supply of Eusideroxylineae (Kostermans 1957). seeds and seedlings is inadequate. Based Ironwood is one of the most important construction woods in Indonesia. The on the IUCN red list of threatened wood is used for making furniture, species, E. zwageri’s category and window and door frames, harbors, heavy criteria are VU A1cd+2cd. This means construction, roofs, bridges, railway that ironwood is not critically endangered sleepers, marine pilling, boat or endangered but is facing a high risk of construction, fence posts, heavy duty extinction in the wild in the medium- industrial flooring, shingles and vehicle term future (IUCN 2014). body work. The most valuable characteristic of Oldfield et al. (1998) showed that ironwood is that it is not vulnerable to termites and other ubiquitous tropical ironwood is included in the list of threatened tree species. Its decline was wood-eating insects and fungi. For this reason, the wood is in great demand for 175 J. Ilmu Teknol. Kayu Tropis Vol. 14 No. 2 Juli 2016 construction throughout Indonesia green to oven dry are 4.2 and 8.3%, (Peluso 1992). Martawijaya et al. (1989) green and air dry modulus of elasticity explained that the physical are 174000 and 184000 kg cm-², green characteristics of ironwood are excellent. and air dry compression parallel to grain Class of strength is one, durability class are 665 and 734 kg cm-², green end is one, and it is very hard, with a specific hardness is 973 kg cm-²; and green and gravity of 0.88-1.19. Additionally, Wong air dry tensile strength parallel to grain et al. (1996) explained that ironwood is are 48.2 and 26.7 kg cm-². Kostermans et found to be very resistant to fungi in a al. (1994) reported that compression fungal decay test. Sampling of ironwood parallel to grain is 683.7-816.3 kg cm-² heartwood poles in Sarawak revealed and compression perpendicular to grain only surface biodeterioration after 20 is 178.6 kg cm-². The rate of shrinkage years in ground-contact. Furthermore, from green to oven dry is rather high: although the wood is impermeable to 4.2-4.3% radial and 7.5-8.3% tangential. preservatives, it can be used in severe Ironwood dries slowly, although the decay hazard environments (soil burial). moisture content of green wood is comparatively low (about 38%). Ironwood belongs to the heaviest wood species. Its volumetric swelling and Four varieties of ironwood namely exilis, swelling anisotropy are almost 15% and grandis, ovoidus and zwageri had been 1.73, respectively. The moisture content identified based on morphological of green wood amounts to 44.16%. characteristics and genetic marker Bending strength is 17744.9 kg cm-², the (Irawan 2005, Irawan et al. 2015). It has crushing strength comes to 867.3 kg cm-² never been determined that there is a and the impact bending to 0.92 kg cm-². correlation between mechanical wood The results of mechanical testing confirm properties and other botanical the suitability of ironwood as construction characteristics (Koopman & Verhoef timber (Scharai-Rad & Sulistyobudi 1938). However, some researchers found 1985). that some important physical properties Almost the same averages of modulus of are moisture content, radial shrinkage, elasticity were reported by some studies. tangential shrinkage, and density have Scharai-Rad and Sulistyobudi (1985) been reported to be influenced by genetic reported the value of modulus elasticity factors (Cave & Walker 1994, Ying et al. 1994). is about 196939 kg cm-², Martawijaya et al. (1989) reported it ranges from 174000 Materials and Methods to 184000 kg cm-², and Kostermans et al. (1994) reported its value ranges from Sample collection and methods - 177550 to 184690 kg cm ². Wood density Sample logs were collected from Senami was reported to vary between 0.88 and forest, Jambi, Indonesia. Four logs of E. -3 1.19 g cm (Martawijaya et al. 1989) zwageri were used as samples for - and (0.83-) 0.88 (-1.19) g cm ³ mechanical property tests. The size of the (Kostermans et al. 1994). logs was 25 cm dbh. They were cut at Furthermore, Martawijaya et al. (1989) 100 cm above soil surface with length of wrote that physical and mechanical 100 cm. The sample logs were properties of ironwood are as follows: recognized as representing four varieties radial and tangential shrinkage from of ironwood namely - exilis, ovoidus, Physical and Mechanical Properties of Four Varieties of Ironwood 176 Bambang Irawan zwageri and grandis- were used to measured by pressing a steel ball into the explain wood properties of investigated sample. The maximum load required to logs. The samples were investigated at embed the ball to one-half its diameter is the Laboratory of Forest Product the value of side hardness. Technology at Bogor Agriculture University, Indonesia. Parameters and statistical analysis From each log one set sample was taken Macroscopic features which were which consisted of five unit samples for observed were wood color, wood texture, physical and mechanical property wood fibers, and wood hardness. In investigation. The size was (5x5x55-70) addition to those four parameters, cm3. The Physical and mechanical investigation was also conducted to property test was referred to British determine vessel elements, including Standard (BS) 375-57. Water content vessel distribution, size and frequency; was measured by Gravimetry method. rays, including type, size and frequency; The sample size was (1x2x2) cm3. The type of axial parenchyma; tree rings; and samples were weighed and dried in an color differentiation between early wood oven at a temperature of (103±2) °C until and late wood. Microscopic features they reached constant weight. Water investigated included proportion of rays, content was calculated by the formula: proportion of fibers, proportion of {(first weight-constant weight)/constant parenchyma, and proportion of vessels. weight} x 100%. The following parameters of physical Density was measured by the standard and mechanical properties of sample logs method in which density is the were investigated: green and dry air comparison of the constant weight of moisture content (%); radial shrinkage of wood to its green volume. The green green to oven dry (%); radial shrinkage volume was calculated based on the of green to air dry (%); tangential principle of Archimides. Sample size shrinkage of green to oven dry (%); was (1x2x2) cm3. Shrinkage tests were tangential shrinkage of green to air dry conducted using sample sizes of (%); density (g cm-³); green and air dry (5x5x0.6) cm3 for tangential shrinkage hardness (kg cm-²); green and air dry and (2x2x2) cm3 for radial shrinkage. modulus of elasticity (MOE) (kg cm-²); The shrinkage was measured from green green and air dry bending strength condition to air dry and oven dry. (MOR) (kg cm-²); green and air dry tensile strength parallel to grain (kg cm-²) Bending strength and modulus of green and air dry compression parallel to elasticity were tested using an AMSLER grain (kg cm-²). Data were analyzed universal testing machine with a capacity using analysis of variance, Duncan of 6000 kg. The sample size was 3 multiple range test, and discriminant (2x2x24) cm . The samples were analysis and clustering, which was pressured centrally until they were performed using UPGMA cluster destroyed. Tensile strength parallel to analysis. The software package used was grain and compression