Properties of Celtiz zenkeri Engel: a lesser-known timber species from Kilindi District, Tanzania

Abstract

This study was conducted to provide some of the basic physical and strength properties of wood of Celtis zenkeri Engel. which is among the lesser-known and lesser-utilized timber species from Tanzania. Celtis zenkeri belonging to the family Ulmaceae is currently being harvested for wood fuel and building poles thus being under-valued and placed in class V timbers since the basic properties of its wood are not yet known. The objective of this study was therefore, to determine and assess some of the basic physical and mechanical properties of C. zenkeri specifically colour, texture, basic density, Static bending (Modulus of Flasticity, Modulus of Rupture, Work to maximum Load and Total work), Compression parallel to grain, Shear and Cleavage stress. Relationships between basic density and the mechanical properties were also assessed. Data for this study were collected from three mature and defect free sample trees objectively selected from Kilindi district in Tanga region. Each sample tree produced three logs; from bottom, middle and upper part of the bole. Test specimens were extracted from the samples and by using standard methods, the physical and mechanical properties were determined. The following are the wood strength properties obtained for C. zenkeri. Basic density (655 kg m-3) and Total Work (21,916 N mm-2), Modules of rapture (198 N mm-2), Work to maximum load (0.360 N mm-3) and Total Work (0.598 N mm-2). Others are; Cleavage strength (24.56 N mm-width), compression strength (97.1 N mm-2) and Shear strength (28.7 N mm-1) Celtis zenkeri wood was found to have desirable values to be used for hand tools, joinery, building, plywood, artificial limbs and flooring furniture.

Key words: Basic density - Tanga, Khaya anthotheca, Eucalyptus paniculata, Fagaropsis angolensis