Variation In Basic Density, Fibre And Vessel Morphology Of Eucalyptus Tereticornis Sm. Clones
The basic density, fibre and vessel morphology of five clones of Eucalyptus tereticornis developed by ITC Bhadrachalam were reported. The five clones represented by four trees each of four and half years old, were from Sarapaka, Andhra Pradesh. Significant variation have been found among the clones. Basic density is positively correlated with fibre length, vessel diameter and positively correlated with vessel frequency while other characteristics have no effect. The results obtained in this study have shown the suitability of raw material for paper and pulp where the required basic density is met with. Mainly these clones are primarily tried to meet the requirements of paper and pulp industry.
Studies on physical, chemical and fibre morphological parameters of three pulpwood species viz. Eucalyptus, Melia and Casuarina for pulp and paper making
Investigations were made on the physical, chemical and fibre morphological parameters and fibre derived indices of three pulpwood species viz. Eucalyptus, Melia and Casuarina for pulp and paper making. Eucalyptus, Melia and Casuarina trees were selected, felled and wood samples were collected from respective plantations established in Forest College and Research Institute, Mettupalayam. Basic density of wood samples were measured using Shimadzu electronic balance attached with specific gravity module. Fibre maceration was done by Jeffrey’s method and holocellulose and lignin content by Tappi method. Basic density and fibre morphological parameters showed significant variation (at 1%) between species. The highest basic density was observed for Casuarina followed by Eucalyptus and the minimum for Melia. The high fibre length and fibre wall thickness was observed for Casuarina followed by Eucalyptus and Melia. The fibre diameter and fibre lumen width was highest for Melia followed by Casuarina and Eucalyptus. Chemical composition was almost same for all the species; holocellulose ≈73% and lignin ≈23%. Studies on suitability of species for paper making showed that Eucalyptus is preferred in terms of its moderate basic density and optimum fibre morphological parameters. Low fibre length of Melia and high fibre wall thickness of Casuarina adversely affected its paper making properties. However in terms of fibre derived indices, Melia dubia was found to be most suitable for paper making followed by Eucalyptus and Casuarina.
Effect of stress conditions on collapse deformation behavior of a rockfill material
A set of saturated and dry-saturated large-scale triaxial tests were conducted in order to explore the effects of stress conditions on the saturation-induced collapse deformation behavior of a rockfill material. Specimens were tested in different confining pressures and for dry-saturated tests the specimens were submerged in various shear stress levels. The results indicate that in all of the dry-saturated tests a sudden reduction in the volume of the specimens was observed during the submerging process. The ratio of the minimum axial strength of a submerged specimen (at the end of the saturation process) to the shear strength of the specimen before saturation is defined as the coefficient of stress recovery, Csr. Results of the dry-saturated tests showed that this ratio increases as the confining pressure increases and decreases by increasing the shear stress level. According to the results of dry-saturated tests the values of internal friction angle reduction caused by saturation (Δϕc), the ratio of the elasticity modulus of the material after saturation to its elasticity modulus in dry condition, i.e., Ewet/Edry, and also the saturation induced sudden volumetric strain (εvc) decrease as the confining pressure increases. However the shear stress level does not have any meaningful effect on the variation of Dfc, Ewet/Edry and (εvc).