Search

Siting of buildings in rural urban development requires that the prevalence of termite activities is considered. The severity of termite activities across 18 selected locations within the FUTA campus was investigated. Defect-free samples of Pterygota macrocarpa wood species prepared according to ASTM D3345-17 (2017) were used as baits for assessing the severity of termite activities. The termite severity probability map of the campus area was prepared with the results obtained from the ASTM D3345-17 visual rating and corresponding gravimetric weight loss data. Results revealed the presence of four termite species within the FUTA campus, namely Macrotermes subhyalinus Rambur, Amitermes evuncifer Silvestri, Ancistrotermes cavithorax Sjostedt, and Microtermes spp.; the latter being the most prevalent. Areas where Macrotermes subhyalinus Rambur were present experienced higher severity and aggressive termite activities with lower visual ratings and higher weight loss values. Supporting soil property data shows that only the soil bulk density had a strong positive correlation with the severity of termite activities with rs = 0.808 and P = 0.001. The termite severity probability map from these data revealed active ongoing termite activities with sharp transitions observed between the regions belonging to the different severity (color coded) levels. This study has reinforced the necessity for estate developers to carry out termite severity assessment in order to recommend appropriate constructional techniques that will ensure the protection of wood in service.

Biomass is the most utilized form of renewable energy, especially in developing nations, and is a possible replacement for fossil fuel in power generation. The most commonly used method for recovering energy from biomass is combustion. Many countries are exploring the utilization of energy crops and indigenous residues to deliver sustainable sources of biomass. For these bio-resources, detailed characterization of the fuel properties is essential in order to optimize the combustion processes. In this study, some potential energy crops and woods from Nigeria, namely Terminalia superba, Gmelina arborea, Lophira alata, Nauclea diderrichii, and also one abundant agricultural residue, palm kernel expellers (PKE), were characterized for their combustion properties. Standard characterization methods such as proximate and ultimate analyses, metals analysis, and ash fusion test were used for this purpose and the results were compared with some U.K. biomass. In addition, their thermal conversion was assessed by thermogravimetric analysis and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). Finally, combustion studies were conducted by suspending single biomass particles in a methane flame to obtain information on reactivities and combustion characteristics. Results indicate that the ash fractions in the Nigerian woods were low in K, Si, and Ca, resulting in low calculated alkali indices, hence these fuels are not predicted to cause severe fouling problems. Furthermore, the analysis of the evolved product during devolatilisation from Py-GC-MS suggests that the content of oil is high in Gmelina. Finally, the results from the single particle combustion experiments revealed a longer char burn out rate for Lophira and Nauclea when compared with those of Terminalia and Gmelina.

Surface chemistry, thermal stability and rheological behaviors of Mansonia (Mansonia altissima), Sapele mahogany (Entandrophragma cylindricum), Lagos mahogany (Khaya ivorensis), Utile (Entandrophragma utile), Osan (Aningeria altissima), Obeche (Triplochiton scleroxylon) and Danta (Nesogordonia papaverifera) were determined. Chemical components of the wood surface were investigated using Fourier transform infrared spectroscopy; the infrared spectra obtained differed among species. The holocellulose to lignin ratio was estimated for some of the wood species. Thermogravimetric analysis indicated that thermal stability and the rate at which each wood polymer degraded are wood species dependent. The viscoelastic properties of these wood species were tested while submerged in ethylene glycol solvent under saturated conditions using dynamic mechanical analysis. The results show that at 0.1 Hz, the glass transition temperature of Obeche is 85 ± 1 °C while other species have it at higher temperature. However, ethylene glycol saturated Sapele mahogany has the highest storage modulus from 120 to 0 °C.

The technical properties of three layered cement-bonded boards (CBBs) made from wastepaper and sawdust were investigated. The CBBs were produced at three density levels of 1000, 1200 and 1300 kg/m3 and at four cement/particle ratios of 2.0:1, 2.5:1, 3.0:1 and 3.5:1 on a weight to weight basis. The technical properties evaluated were modulus of rupture (MOR), modulus of elasticity (MOE), water absorption (WA) and thickness swelling (TS). The MOR values ranged from 4.85 to 11.69 MPa and MOE values ranged from 2.80 to 5.57 GPa. The mean values of WA and TS after 24 h of water soaking of the CBBs ranged from 18.18% to 40.49% and 3.55% to 12.13%, respectively. MOR and MOE of the CBBs increased with increase in board density, but MOR decreased with the increase in cement/particle ratio. On the other hand, WA and TS decreased with increase in board density and cement/particle ratio. CBBs produced from wastepaper and sawdust at cement/particle ratios of 3.0:1 and 3.5:1 are suitable for building construction such as paneling, ceiling and partitioning.

The above-ground biomass yield of seven-year-old trees of Gliricidia sepium, Gmelina arborea and Leucaena leucocephala grown for fuel production were assessed. The combustion properties of the fuelwood and charcoal produced from the trees (moisture content, density, percentage fixed carbon, volatile matter, micro-elemental composition and heat of combustion) were determined. There were significant differences in the above-ground biomass and the charcoal yield from the various species. The stand biomass was 37.4 t/ha for Gliricidia sepium, 85.6 t/ha for Gmelina arborea and 46.2 t/ha for Leucaena leucocephala. The charcoal yield (range 25–42%) was highest in Leucaena leucocephala. The average heat of combustion of charcoal, 33.25 MJ/kg, was higher than that of wood, 21.6 MJ/kg. Gmelina arborea gave the greatest energy yield per hectare due to its high stand biomass.

The high cost of conventional fossil fuels has resulted in a rise in the demand for charcoal in developing countries. There has been a problem of wood scarcity and indigenous tree species are being replaced with the fast-growing, short-rotation species. Three short-rotation tree species: Gliricidia sepium, Leucaenea leucocephala and Gmelina arborea were converted to charcoal by a pyrolytic process. The effects of final carbonisation temperature on the yield, heating value and proximate analysis of charcoal from the tree species were determined. Gliricidia sepium gave the highest charcoal yield of 51.6% with a gross heating value of 31.45 MJ/kg at 300°C final carbonisation temperature. There was no significant difference in the charcoal yield of Gmelina arborea and Leucaena leucocephala at 5% level of testing. The charcoal yield decreased with an increase in carbonisation temperature. The percentage volatiles in charcoal decreased with an increase in temperature, while there was an increase in the percentage fixed carbon.

The utilization of fuel wood as a major source of primary energy in Africa was reviewed with a focus on its management in secondary forests. Fuel wood sources, the state of regional energy crises, and the silvicultural management of fuel wood in secondary forests are all factors that were considered in this study. About 95% of fuel wood consumed in the continent is from secondary forests and is used for both domestic and industrial purposes. Its consumption varies with vegetation distribution, population density, demographic characteristics, and the state of local energy crises. Preventing the loss of forest resources through deforestation is the greatest challenge of fuel wood utilization. Silvicultural practices for management of fuel wood include natural regeneration, coppice, coppice with standard, and agroforestry techniques. The great demand for wood production through these methods had led to an increase in intensive forest management and the adoption of community participatory approaches in the formulation and implementation of forest policy.

Charcoal was produced from short rotation tropical species ofLeucaena leucocephala andTectona grandis. The combustion-related properties, moisture content, specific gravity and percentage element composition of carbon, hydrogen, oxygen, nitrogen, sulphur and ash in wood and charcoal from the two species were determined. The gross heat of combustion of wood and charcoal was also determined. There were significant differences in the moisture content, specific gravity and percentage element composition between wood and charcoal from the two species. The carbon and ash content of charcoal were higher than those of wood. The average heat of combustion of charcoal 25.25 MJKg−1 was higher than that of wood 13.75 MJKg−1.

A solar timber kiln with the capacity to season 3·24 m3 of lumber was designed, constructed and used for seasoning commercial sawnwood. The kiln was constructed of a timber frame covered with transparent polythene sheet on the top and black leatherette on the sides. Corrugated, galvanized-iron sheet painted black and tilted at 30° to the horizontal served as a heat collector. Two fans were fitted for air circulation. The kiln attained a maximum temperature of 24° above the ambient temperature. The average efficiency of the heat collector was 38·5%. The solar kiln reduced timber drying time by 33·3–57·1% when compared with an air-drying technique. Sawnwoods (25 mm by 300 mm by 360 mm) of Mansonia altissima and Terminalia superba were dried from 46·16 to 15·02% and from 52 to 15·4% moisture content respectively in 12 days.

Two types of tannin-phenol formaldehyde adhesives — (i) a mixture of 70% Mangrove tannin and 30% phenol formaldehyde (PF) and (ii) a mixture of 70% Quebracho tannin and 30% PF — were used in the fabrication of two sets of particleboards. The third set of boards was prepared using 100% PF resin. The bending strength and internal bond strength of the tannin-PF bonded boards met the specifications required for commercial boards. The modulus of rupture, modulus of elasticity, internal bond and dimensional stability of the PF bonded boards were higher than those of the tannin-PF boards. Mangrove tannin-PF boards had better bending strength and dimensional stability than Quebracho tannin-PF boards.

Samples of kenaf ( Hibiscus cannabinus ) grown in Nigeria were examined to determine the kraft pulp and papermaking properties of their bast fibres. The average length of kenaf bast fibre was 2·66 mm while the kraft pulp yield was 58·1%. The strength properties of hand sheets were better than those of hardwood pulp but similar to those of softwood. Kenaf is considered promising for production of high-grade printing, writing and specialyy papers.

The gross heat of combustion of holocellulose, α-cellulose, lignin and extractives isolated from Gmelina arborea (Roxb) were determined to be 19715, 19704, 25383 and 25137 kJ kg −1 , respectively. The bark and leaves which contained relatively high proportions of lignin and extractives had the highest heat of combustion on dry, ash-free basis.

The paper reports on the potential for utilization of residues from wood-based industries as sources of energy for production processes. The combustion properties of six common wood species were determined and these were used in estimating the heat energy derivable by burning wood residues accruing from pulp and paper production in Nigeria. It was estimated that 9·4–33·3% of heavy-oil requirements could be replaced by burning wood residues in three Nigerian pulp mills.