By: OWOYEMI J. M.; OWOLABI J. K.; ALADEJANA J. T.;
Abstract:
The search for a new preservative has been necessitated by concerns about the health and environmental hazards associated with use of conventional ones. Bituminous tar available in large quality in Nigeria was administered to evaluate its effect on resistance of Albizia ferruginea (ayinre), Melicia excelsa (iroko), Pterygota macrocarpa (Oporoporo), Triplochiton sceleroxylon (Obeche) and Celtis zenkerii (Ita) to termites. Wood samples of 35 × 35 × 450mm stakes were dried in the oven at 103 ± 2oC for 24h and treated in hot bitumen at 200oC for 6h and left overnight after the treatment. The stakes were planted at the termites’ graveyard for visual and weight loss assessment after 12weeks. The bitumen attained boiling point of 200oC with viscous flow of 0.4 cm3/sec at 150?C which causes reduction in moisture content of the wood samples. Ita and Iroko had the higher density values of 565.28 and 506.7kg/m3 respectively while Obeche had 405.99kg/m3. There is significant difference between the resistance of treated and untreated samples at 5% level of significance. Pearson correlation coefficients of 0.922 and 0.920 for density and wood resistance showed that high density wood is more resistant to termites attack. Bitumen has proven potent as preservative for treating timber for external uses such as transmission poles, fence posts and wharf jetty.
Keywords: Heartwood; Sapwood; Termites; Bitumen; Graveyard
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