Suthon Srivaro

Comparison of physical and mechanical properties of Dendrocalamus asper Backer specimens with and without nodes

This study investigated the effects of nodes on some of the physical and mechanical properties of Dendrocalamus asper Backer (D. asper Backer). Two types of D. asper Backer specimens, with and without nodes, were prepared from the bottom and top parts of the bamboo culms for testing of their physical (density, water uptake, shrinkage and swelling) and mechanical (shear strength parallel to the grain, tensile strength parallel to the grain, modulus of rupture and modulus of elasticity) properties. The results obtained for the two types of specimens were then compared. The results showed that the radial swelling and shrinkage properties, the tensile strength parallel to the grain and the modulus of rupture values of specimens with nodes were significantly lower than those of specimens without nodes at both culm height positions examined. The other properties along the culm’s height were not significantly different for the two specimen types. The results indicate that node effects should be considered as part of the practical design of D. asper Backer bamboo products, especially when bamboo with nodes is used.

Comparison of the anatomical characteristics and physical and mechanical properties of oil palm and bamboo trunks

The aim of this work was to investigate the structure–property relationships of two different monocotyledon trunks: bamboo (Bambusa blumeana Schultes) and oil palm (Elaeis guineensis Jacq). Anatomical characteristics (fraction of fibers) and physical (density, water uptake, and swelling in the radial direction) and mechanical (modulus of rupture and modulus of elasticity) properties of bamboo and oil palm trunks were examined. The results showed that the examined properties of both species were mainly governed by fibers. Those of bamboo were mostly greater. Functions relating most of the examined properties to the density of both species were finally achieved. Based on the results obtained, it is suggested that bamboo has a higher potential for structural application, while oil palm wood is more likely to be utilized for non-structural purposes.

Property gradients in oil palm trunk ( Elaeis guineensis )

Since the structure of oil palm wood varies dramatically, the property gradients of oil palm wood within a trunk are of great interest. In this study, the physical (density, water uptake and swelling in the radial direction) and mechanical properties (bending modulus of elasticity and strength, compressive modulus of elasticity and strength in the direction parallel to the fiber, compressive strength in the direction perpendicular to the fiber and shear strength in the direction parallel to the fiber) of oil palm wood for a whole trunk were examined. The water uptake, compressive strength in the direction perpendicular to the fiber, shear strength in the direction parallel to the fiber, bending modulus of elasticity and strength and compressive modulus of elasticity and strength in the direction parallel to the fiber appeared to be independent of trunk height but tended to be related to the relative distance from surface or density by a single master curve. However, the swelling in the radial direction of the oil palm wood was not correlated with the relative distance from the surface, trunk height or density. Finally, property map of oil palm wood for a cross section at any height was prepared for practical use.

Potential of three sympodial bamboo species naturally growing in Thailand for structural application

This study evaluated the performance of three sympodial bamboo species naturally growing in Thailand including Pai pa (Bambusa bambos (L) Voss), Pai lummarok (Bambusa longispiculata Gamble) and Pai seesuk (Bambusa blumeana Schultes) with respect to its use as alternative material for building construction. Their anatomical structures and densities were first analyzed. Then, the mechanical properties of these bamboo species were examined and compared with those of structural woods, structural bamboo products (SBPs) and steel. Node effect on mechanical properties of bamboo was also examined. The result showed that most of the mechanical properties examined increased with density regardless of bamboo species type except for shear strengths in longitudinal-tangential plane which seemed to be independent of density and bamboo species type. They were similar for all bamboo species examined. The presence of nodes reduced bending and tensile strengths for all bamboo species examined. Nevertheless, most of the remaining strengths were still similar to or greater than that of structural woods and SBPs, but the remaining tensile strengths were lower than that of steel by about a half. This result indicates that all bamboo species examined have high potential for structural applications.