Browsing by Author "Makonda, F. B."

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Basic density and strength properties of Pines in Uganda
(African Journals Online (AJOL), 2008-02-21) Ishengoma, R. C.; Odokonyero, G.; Makonda, F. B.; Hamza, K. F.
Basic density and strength properties and their variations in 25 year - old Pinus caribaea, P. oocarpa and P. kesiya grown in Katugo, Uganda were investigated. Six trees for each species were selected representing three diameter classes. The trees were felled after measuring their diameter at breast height. Three disks were cut from each tree at 1.3 m, 45% and 75% of total tree height for growth ring width and basic density assessment. For strength properties determination, a central plank measuring 65 mm thick was extracted from each sample tree starting at breast height upwards. Basic density was determined using water displacement. Tests of various strength properties were done in accordance with standard procedures. The data were analyzed using the Statistical Analysis System. Results for the studied properties of Pinus caribaea, P. kesiya and P. oocarpa respectively were as follows: Basic density: 424, 431,and 444 kg/m3; Modulus of rupture: 54.51, 56.31 and 60.69 N/mm2; Modulus of elasticity: 8590,8752 and 8825 N/mm2; Work to maximum load: 0.088. 0.099 and 0.101 mmN/mm3; Maximum compression strength: 33.38, 33.83and 34.66 N/mm2; Maximum shear strength: 9.43, 9.80 and 10.37 N/mm2 and cleavage: 11.79,12.15 and 12.48 n/mm. There were no significant differences in all wood properties between the three species. Between tree variations in wood properties were statistically insignificant (p<0.05) in all the species, indicating a low potential of improving wood quality through selection. Growth rate had no significant influence on wood properties. Wood properties studied decreased significantly from stump upwards the stem and increased from pith outwards in the three species. Strength properties of the three pine species were strongly correlated to basic density with regression coefficients (R2) of above 0.88. Wood strength property values obtained in this study were within the range of pines grown in Kenya and Tanzania. These findings indicate that there are possibilities of expanding the use of these species through promotion. Butt end logs and inner wood can be used for non-structural applications and the outer wood for structural purposes.
Some physical and mechanical properties of Uapaca Kirkiana, a lesser-known timber species from Tanzania
(Tanzania Journal of Forestry and Nature Conservation, 2007) Gillah, P. R.; Makonda, F. B.; Ishengoma, R. C.; Kadala, B.; Kitojo, D. H.
This study was carried out to determine some physical and mechanical properties of Uapaca kirkiana a lesser known timber species growing in public land near Iyondo Catchment Forest Reserve, Kilombero District, Morogoro, Tanzania. A total of 3 trees were used in the study. Preparation of test samples and laboratory procedure to determine some physical and mechanical properties followed standard methods. Analysis of variance was used to determine the variation between and within trees and regression analysis was used to determine relationship between wood basic density and mechanical properties. The results showed that Uapaca kirkiana has whitish sapwood and dark brown heartwood, with a mean basic density of 518.14 kg/m3. The properties of Uapaca kirkiana were as follows: modulus of elasticity (7185.69 N/mm2), modulus of rupture (59.7 N/mm2), work to maximum load (0.06 mmN/mm3), total work to failure (0.07 mmN/mm3), shear strength parallel to the grain (11.86 N/mm2), compression strength parallel to the grain (34.4 N/mm2) and cleavage strength (20.21 N/mm width). On axial direction, the modulus of elasticity, total work to failure, compression strength parallel to grain and cleavage strength were directly proportional to its basic density while modulus of rupture, work to maximum load and shear strength parallel to the grain were inversely proportional implying that Uapaca kirkiana is suitable for activities, which require high modulus of elasticity, total work to failure, compression strength parallel to the grain and cleavage strength. On radial direction modulus of elasticity, modulus of rupture, work to maximum load, compression parallel to the grain and cleavage strength were directly proportional to basic density while shear parallel to the grain was inversely proportional to basic density. Compared to Khaya anthotheca, the timber species found in the same location and market; it was found that the timber of Uapaca kirkiana had modulus of rupture and compression parallel to the grain far lower than those of Khaya anthotheca, while the work to maximum load, total work to failure, shear strength parallel to grain and modulus of elasticity were almost the same. Due to the similarity in some of their physical and mechanical properties, the wood of Uapaca kirkiana may berecommended to substitute Khaya anthotheca in wood works that require medium density wood like in decoration where colour is considered an important aspect for appearance and in cabinet, panel and furniture making though it is not adequate in high-class strength joinery.