This study investigated the physical and mechanical properties of Shea Tree timber (V. paradoxa) for structural use obtained at different areas of Kwara State, Nigeria. Physical properties of the samples like moisture content, specific gravity and density was evaluated and the mechanical tests were tensile strength, modulus of rupture, modulus of elasticity, compression, shear and hardness. Results show that, the density of the specie varied from 1.05 to 1.48 (g/cm3), and specific gravity varied from 0.98 to 1.39. For the mechanical properties, the results revealed that at 18% moisture content and 80% grade stress, mean MOR of 28.91(N/mm2), mean MOE of 9,108 (N/mm2), compressive strength parallel to grain of 24.7 (N/mm2), compressive strength perpendicular to grain of 8.99 (N/mm2), shear strength of 2.01 (N/mm2), and tensile strength parallel to grain of 16.15 (N/mm2). Finally, according to BS 5268-2 (2002) the specie was characterised into strength classes between D50 and D70. The results obtained showed that Shea Tree is a hardwood and suitable to be used for structural engineering purposes. ©JASEM https://dx.doi.org/10.4314/jasem.v21i5.24

Abundant aquatic animal by-products are available in Nigeria which include clam, oyster, rock Snail and periwinkle shells. These are usually dumped on open lands without any economic value after fleshy parts of these animals had been consumed by humans, hence, result into environmental problems. In the agricultural sector, Rice husk and Palm oil fuel ashes are by-products from rice and palm oil industries after the husks have been used as source of fuel. Disposal of these wastes are always a major issue as they constitute nuisance to the environment. This research has collected and characterized these wastes in the laboratory to ascertain their suitability as supplementary cementitious materials. With this study, physical properties such as particle size, specific gravity, specific surface area and morphology are conducted by Scanning Electron Morphology, SEM; chemical analysis are carried out with the aid of X-ray Fluorescence (XRF), for microstructure examination, X-ray Diffraction (XRD) machine is used for detecting minerals in the materials while Field Emission Scanning Electron Microscopy and Energy-Dispersive X-ray analysis (FESEM-EDX) are used for image and element detection. The results of these analyses will help in the future work of pozzolanic and geopolymer construction in Nigeria. The results are further compared with previous literature to see their compatibility and discrepancy.

This study investigates the physical and mechanical properties of two timber species for structural use. Three logs of each specie were obtained at different areas of Kwara State, of Nigeria which is located north in the periphery of the south-western rain forest area, sliced into 2" by 12" size before seasoning naturally and their structural/strength properties were determined at a moisture content of 18%. These logs were cut into test samples for the determination of their properties. A total of 351 samples (45 samples for each test) free from visible defects was used for each specie. Basic physical properties of the samples like moisture content, specific gravity and density was determined. Tensile strength, modulus of rupture, modulus of elasticity, compression, shear and hardness were the mechanical tests carried out according to BS 373 (1957), CP112 (1971), NCP2 (1973), EC5 (1995 and BS 5268 (2002) specifications on Universal Testing Machine (UTM). Results were analysed statistically using Analysis of Variance (ANOVA). A. Indica was graded into strength class D40 while X. Aethiopica was grade into strength class D70.

No abstract

Geopolymer concrete and mortar have evolved over the years as potential alternatives for reducing the greenhouse gases associated with cement production. This current research was aimed at investigating the optimum dosage and concentration of sodium hydroxide required to leach out silica and alumina oxides in the fly ash for geopolymerization to take place. Blackish grey fly ash from Morupule, Botswana, was synthesized by varying sodium hydroxide (NaOH) of 98% purity between 8 M and 14 M, respectively. The ratio influence of sodium hydroxide to fly ash in dissolving the oxides was carried out at the values of 0.55, 0.62, and 0.75. The results showed that the workability of the geopolymer mortar and paste decreased with the increase in the ratio of fly ash to alkaline activator. The highest workability was achieved at a ratio of 0.75 : 1. The compressive strength, setting time, and workability of geopolymer mortar and paste can be controlled by adjusting the ratio of fly ash to alkaline activator. A ratio of 1.5 : 1 was found to be the most suitable for achieving high compressive strength, while a ratio of 0.75 : 1 was found to be the most suitable for achieving high workability. Furthermore, the workability values were in the range of 105 to 143 mm, while the ranges of initial and final setting times were found to be between 280–350 and 950–1170 minutes, respectively. This study is significant because no previous study has carried out geopolmerization of the Morupule fly ash as a result of its unique characteristics. These findings have important implications for the development of sustainable construction materials. The main finding was that for optimum reaction to take place, and NaOH/fly ash ratio should be kept at 0.55 and molarity of 12 to avoid leaching of other oxides that might weaken the strength.