A comparison of some mechanical properties of branchwood and stemwood of terminalia ivorensis and aningeria robusta

In Ghana, wood wastage problem has become national outcry and its solution has not received the attention it deserves. The utilization of stem, branches, stumps, etc can help reduce wood waste and also ensure sustainable utilization of the scarce timber resource. To recommend timber resource as a structural raw material for processing it is expedient that the strength properties are determined. It was against this background that the strength properties (static bending, shear and compression strengths) of branchwood and stemwood of Terminalia ivorensis (Emire) and Aningeria robusta (Asanfena) were assessed to predict the suitability of the species for structural raw material for downstream processing. The results of each strength property of the branchwood of each species were compared with that of the corresponding stemwood. Also, specific gravity and moisture content of fresh samples of Emire and Asanfena were determined. The results were analysed statistically with student’s t-test and z-test to assess the significant difference between the various relationships. It was found out that, modulus of rupture of stemwood of Terminalia ivorensis and Aningeria robusta was 85.31N/mm2 and 90.46N/mm2 while their respective branchwood had 82.42N/mm2 and 88.64N/mm2. At 5% level of significance, modulus of rapture of Terminalia ivorensis and Aningeria robusta was significantly higher than that of the respective branchwood. However, the shear and compression strengths parallel to grain of branchwoods of Emire and Asanfena were higher than their corresponding stemwood. Shear strength of branchwood of Terminalia ivorensis and Aningeria robusta was respectively 13.40N/mm2 and 1 8.70N/mm2 while that of their corresponding stemwood had l2.69N/mm2 and 15.58N/mm2. The statistical results at 5% level of significance showed that there was no significant difference between the shear strength of branchwood and stemwood of Emire but in the case of Asanfena the difference was significant. The compression strength parallel to grain of branchwood of Emire and Asanfena was 48.10N/mm2 and 61.3N/mm2 respectively. The resistance of stemwood of Emire and Asanfena to compressive stress was also 40.70N/mm2 and 5O.57N/mm2 respectively. The results did indicate that compression strength of branchwood of Emire and Asanfena was significantly stronger than the corresponding stemwood at 5% level of significance. Specific gravity of branchwood of Emire and Asanfena was significantly higher than the respective stemwood at 5% level of significance. The relative density of branchwood of Emire was 0.46 and the corresponding stemwood recorded relative density of 0.44. The nominal specific gravity of branchwood and stemwood of Asanfena was respectively 0.56 and 0.50. Moisture contents of branchwood of Emire and Asanfena were 74.34% and 68.00% respectively while their corresponding stemwood recorded 60.12% and 59.76%. It has therefore been found that branchwood of Emire and Asanfena contained more moisture than their respective stemwood. Moreover the statistical results at 5% level of significance showed that branchwood of Emire and Asanfena significantly contained more moisture than the corresponding stemwood. Nominal specific gravity influenced the strength properties of branchwood of the species. The relatively denser branchwood of Emire and Asanfena recorded higher shear and compression strengths parallel to grain. However the resistance of stemwood of Emire and Asanfena to modulus of rupture was higher than that of the respective branchwood. It was concluded that, the strength properties of branchwood of Terminalia ivorensis and Aningeria robusta compared favourably with those of their corresponding stemwood. Therefore branchwoods of Terminalia ivorensis and Aningeria robusta are potential structural raw materials for downstream processing.

Source: KNUST