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.
On the Structure and Identification of Eucalyptus Species
The wood structure of nine species of Eucalyptus have been studied in detail both under light and scanning electron microscope. They have been distinguished on the basis of various anatomical characters viz. vessel and parenchyma distribution, presence or absence of crystals in parenchyma and percentage of tri-seriate rays, and vestured pit morphology. Though microscopic features do help to some extent in the identification, ultrastrncture of vestured pits of vessels aod fibres have been found more useful in distinguishing different species studied.
Control of reflective cracking
The first is 'fatigue' cracking of the layer. This type of cracking is the result of the application of loads on the pavement and is controlled by appropriate thickness design which 'ill not be discussed in detail here. Thickness design includes not only the design strength and thickness of the stabilised, but other design elements such as delaying reflection cracking, or limiting stresses in the stabilised layer, by adopting a minimum thickness of overlying material. This may include an unbound layer utilising the 'upside down' pavement approach. The actual thickness required of the overlying material varies but for example PIARC (Ref.1) recently reported when the thickness of coated materials exceeds 20 cm the emergence of shrinkage cracks at the surface is generally uncommon; when it is 15 cm thick, the cracks emerge at the surface, but do not shorten the life of the surface course, especially if they are sealed. This experience has been gained 'with legal axle loads of 130 kN, considerably greater than the Australian legal axle load.