Abstract: Demand for wood as structural components has kept increasing. The alternatives available to maintain an adequate supply include the controls to regulate the annual falling rate or to find fast-growing plantation trees as replacements for traditional popular species. Thus, this study focuses on the determination of strength performance of Hevea Brasiliensis at a structural size in green and air-dry condition. The British Standard BS 5820: 1979 method of testing structural size timber was adopted to test the strength properties of this species. For this thesis, the mechanical properties of Hevea brasiliensis that will be discussed is the modulus of elasticity (MOE) in NDT test. The physical properties that affect the strength of timber related to this study are moisture content and basic density. It was found that the strength value of modulus of elasticity was high in air-dry condition with an overall mean value of 14237.03N/mm2 compared to Hevea brasiliensis in green condition with MOE value of 14208.21 N/mm2. The average density in green condition for top and bottom part of Hevea brasiliensis are 795.60 kg/m3 and 825.70 kg/m3. While, the average density in air-dried condition for top and bottom part of this timber species are 659.10 kg/m3 and 756.60 kg/m3 respectively. For samples in green condition, the moisture content is 55.02% for the top part and 55.41% for the bottom part, while samples for the air-dry condition is dried until moisture content reached 18%. At air-dry condition, Hevea brasiliensis classified under light hardwood. This study revealed that the strength properties of Hevea brasiliensis in air-dry condition are higher than in green condition. Also, the density was higher at bottom part compared to the top part of this species.

Keywords: modulus of elasticity, basic density and moisture content.