Kwasi Frimpong-Mensah

Effect of species, particle size and compacting pressure on relaxed density and compressive strength of fuel briquettes

Densification of biomass waste materials has provided a great boost to the utilization of wood and agricultural waste for domestic and industrial fuel. However, the processes involved in the production of this fuel make it more expensive than fossil fuel. This is because densification of wood waste into fuel briquettes is not simple. This paper reports the results of research conducted to determine the effect of species, particle size and compacting pressure on relaxed density and compressive strength in cleft of briquettes produced from sawdust of tropical hardwoods. Briquettes were made using a laboratory hydraulic press. Compacting pressure was varied from 10 to 50 MPa at an interval of 10 MPa. Species used were Triplochiton scleroxylon, Ceiba pentandra, Aningeria robusta, Terminalia superba, Celtis mildbreadii and Piptadenia africana. The results indicate that species, compacting pressure and particle size of sawdust at 5% level of significance have significant effect on the relaxed density and compressive strength in cleft of briquettes produced. The multiple correlation coefficient (R) and adjusted R2 for the regression model between relaxed density of briquettes, and species density, particle size and compacting pressure were 0.93 and 0.87, respectively. Additionally, the multiple correlation coefficient and adjusted R2 for the regression model between compressive strength of briquettes, and species density, particle size and compacting pressure were 0.83 and 0.69, respectively. The regression models suggest that species density, particle size and compacting pressure are good predictors of relaxed density and compressive strength in cleft of briquettes produced from sawdust of tropical hardwoods.

Characterization of moisture content and specific gravity of branchwood and stemwood of Aningeria robusta and Terminalia ivorensis

Aningeria robusta and Terminalia ivorensis of diameters ranging from 10 cm to 25 cm were examined. The following results were obtained: The overall (sapwood and heartwood combined) moisture contents of the branchwood of both Aningeria robusta and Terminalia ivorensis were significantly greater than those of their corresponding stemwood, with the branchwood of Terminalia ivorensis being the highest. It was also observed that the overall specific gravity of the branchwoods of both species was higher than that of the corresponding stemwood, with the branchwood of Aningeria robusta exhibiting the highest specific gravity. Detailed analyses of moisture content distribution and specific gravity of the heartwood and sapwood of Aningeria robusta and Terminalia ivorensis are also presented.

Characterization of mechanical strength properties of coconut wood infested with the Cape St Paul Wilt disease

The mechanical strength properties of coconut wood infested with the Cape St Paul Wilt disease were determined, and thereafter, compared with strength properties of other traditional timber species. Experimental results indicate that coconut wood infested with the Cape St Paul Wilt disease can be used as alternate raw material for furniture, building construction, communication poles as well as other wood based products.

Termite resistance of Klainedoxa gabonensis (kruma), a tropical lesser-utilised-species for commercial utilisation

ABSTRACT The paper describes the testing for termite resistance of a lesser-utilised tropical species known as kruma (Klainedoxa gabonensis) in order to evaluate its potential for the building, construction and related wood-consuming industries. Results suggest that kruma heartwood can be rated as very durable and the sapwood as durable. It is concluded that utilisation of this wood species could reduce over dependence on traditional primary species.

Mechanical properties of coppiced and non-coppiced Pterocarpus erinaceus boles and their industrial application

Rosewood (Pterocarpus erinaceus Poir.) is valued for flooring, ornaments, musical instruments and furniture-making due to its durability, strength, beauty and acoustic properties. It coppices easily which could boost its continual supply. Compression parallel to grain, Modulus of Elasticity (MOE) and Modulus of Rupture (MOR) within coppiced and non-coppiced boles were determined. These properties decreased along both types of boles. Strength values for the heartwood were also greater than those for the sapwood of each type of bole. MOE, MOR and compression for non-coppiced stems were greater than those from the coppiced stems. The differences were significant (p < 0.05). Mechanical properties from the coppiced and non-coppiced boles are comparable. Both have strength properties comparable with those of species widely used for railway sleepers, structural supports, flooring, veneer, furniture, cabinetry, truss and mine props. Therefore, coppiced wood could supplement non-coppiced wood for industrial applications which require strength.

Variation in bending strength properties in stem and branch woods as influenced by density and moisture levels in Entandrophragma cylindricum

ABSTRACT Branchwood is being exploited as a supplement to stemwood in wood products manufacturing, and the wood’s bending strength properties are vital for structural and non-structural applications. Non-destructive methods are being adopted in determining wood properties, and wood density and moisture content are two variables that could be useful. This study assessed the influence of density and moisture content (MC) on the Modulus of Elasticity (MOE) and Modulus of Rupture (MOR) of branch and stem woods of Entandrophragma cylindricum (sapele) tested at two moisture levels (10 ± 4% MC and 17 ± 3% MC). Density was determined in accordance with ISO 3131. To determine bending strength properties, BS 373 was followed, using an INSTRON TCM Machine with a crosshead speed of 6.6 mm per minute. Results indicated that branchwood has higher density than its stemwood counterparts. MOE and MOR of both wood types were significantly higher at 10 ± 4% MC than their counterparts at 17 ± 3% MC. Differences in MOE and MOR between the wood types were not significant, although the branchwood had 87% and 93% respectively of the MOE and MOR of stemwood. From the two-way ANOVA, MC had a significant effect (P < 0.05) but wood type and the interactions of wood type and MC did not have a significant effect on MOE and MOR of stem and branch woods. The predictive powers of MC and density as a combined predictor for estimating bending strength properties were higher for branchwood than stemwood. Although density of E. cylindricum branchwood was significantly higher than its stemwood counterpart that did not translate into significant differences between MOE and MOR of branchwood and stemwood.