International Journal of Engineering Research in Africa Vol. 8

Abstract: Physical and chemical studies were conducted on Afari and Mfensi clays in Atwima Nwabiagya District in Ashanti Region of Ghana, with the view of improving their strength properties by chemical stabilization with cocoa pod ash (CPA) and lime as chemical stabilizers. The idea was to produce stabilized clay brick without firing as an improved building material for the rural housing in areas where the materials exist and beyond. The results revealed an improvement in both dry and wet compressive strengths with the additions of 10% to 15% lime and CPA. The maximum dry compressive strength of 2.07N/mm² and 5.85N/mm² and wet compressive strength of 0.91N/mm² and 2.67N/mm² respectively were recorded for Afari and Mfensi clays. The water absorption also reduced from 100% to 27.59% and 17.78% respectively for Afari and Mfensi clays. Although there were decreases in wet compressive strength on soaking the specimens in water, the stabilized bricks did not disintegrate after 28 days of soaking. Moreover, the stabilized clay bricks showed good durability behaviour and did not disintegrate when exposed in the open air for two years.

Abstract: This paper provides the results of structural reliability analysis carried out on the data of Nigerian grown Iroko tree (Chlorophora excelsa), to ascertain its structural performance as timber bridge beams. Five pieces of 50mm x 75mm x 3600mm of Nigerian grown Iroko hardwood were bought, seasoned naturally and 200 pieces of samples were prepared for determination of their strength properties, (which include bending strength parallel to grain, tensile strength parallel to grain, compressive strength parallel to grain, compressive strength perpendicular to grain and shear strength parallel to grain) at a moisture content of 18%, in accordance with the British Standard BS 373 of 1957. Statistical analysis was carried out using the strength properties for determination of mean, standard deviation, coefficient of variations, confidence limits and Chi-Square goodness of fits. Structural analysis and design of a timber bridge beam using the determined data from the Nigerian grown Iroko timber, in accordance with BS 5268 were carried out under the Ultimate Limit State of loading (ULSL). Reliability analysis was carried out to ascertain its level of safety using First-Order Reliability Method (FORM). Sensitivity analysis was also carried out by varying the depth of beam, imposed live load, breadth of the beam, unit weight of the Iroko timber, span of the beam as well as the end bearing length. The result revealed that the Nigerian grown Iroko timber is a satisfactory structural material for timber bridge beams at depth of 400mm, breadth of 150mm and span of 5000mm under the ULSL. The probabilities of failure of the Nigerian grown Iroko timber bridge beam in bending, shear, compression and deflection are respectively, under the specified conditions of loading.

Abstract: B-Regions are parts of the structure in which Bernoulli's principle of straight-line strain is used. D-Regions are parts of the structure with a complicated variation in strain. In essence, D-Regions contain the parts of structure which are near to the concentrated forces or steep changes in geometry which are so-called geometrical discontinuities or static discontinuities. Strut-and-Tie Model (STM) is one of the best models to analyse the D-regions. Nevertheless, according to the existing literature, there are still some challenges about STM which are addressed in this paper. STM and its details are investigated to show its common challenges presents some recommendations to overcome these challenges. According to this review, the major challenges in STM are related to the strut effectiveness factor, static uncertainties of STM, strain compatibility, and anchorage requirements in STM. The scope of this research is confined to the two dimensional STM.

Abstract: In this study, electrophoretic deposition (EPD) method was used for biphasic calcium phosphate (BCP) coating on 316L stainless steel substrates, using ethanol as a dispersive medium. Deposition was achieved on the cathode at 30 V in 30 seconds at room temperature in variable concentrations (0.5, 0.8, 1, 1.25, 1.5g of BCP powder). After deposition, the coated substrates were sintered at 800 °C for 1 hour. The phase purity and structure of the synthesized powders were checked by X-ray diffraction (XRD). The morphology, structure and phase composition of the coatings were investigated by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The results show that deposition weight and thickness increased with increasing concentration. Furthermore, increases in cracks and changes in morphology on coating surfaces as concentration increased at the constant applied voltage during electrophoretic deposition were observed.

Abstract: This paper aims to assess the impact of financial factors which have a direct bearing on the success or failure of the construction companies. This paper is part of the main study which aims to identify key areas of strategic issues for construction companies in Qatar by using 6S strategic management framework. This research adopts a combination of primary and secondary data using a questionnaire survey involving 115 companies holding 99 per cent of the market share in Qatar. In this case study, a total of 17 financial ratios were employed as performance measurement tools. Interpreting these ratios, typical median (industry average) and typical range were used to compare a companys average ratios. The analyses reveal that most of the construction companies do not have sufficient financial resources, lack of monitoring system for the cash flow, and project costs. Without effective strategic management practices, construction companies are putting their self-up to failure. In addition to comparing the financial health of construction sector, this study aims to fill in the gap by creating basic benchmarks for 17 ratios applicable to construction sector in Qatar.

Abstract: This paper considers the application of Linear Programming (LP) to an investment decision problem of a firm in Ghana. The aim is to maximise the investment of the firm. The investment concern of the firm was first modelled as LP problem and then solved. A sensitivity analysis was subsequently performed on the model to assess its stability to slight variations of some selected parameters. This yielded a range of possibilities for the solution of the model and provided a basis for the selection of the best optimal solution.

Abstract: The small-scale fabrication industry is of great importance to developing an economy. In the last two decades governments and private agencies in Nigeria have demonstrated great concerns in developing the Small Scale Industries through policy formulation and support for agencies created with a view to developing the industry. But such concerns have not yielded any good results. There are therefore some salient problems bedeviling this sector. The work presented in this paper is a study of the constraints to the growth of the small scale fabrication industry in Nigeria using Benin metropolis as a case study. Structured questionnaires were used to collect primary data and interviews were also conducted. The data collected were then analyzed and the constraints to the growth of the industry were identified. The results obtained from the study showed that non awareness of government policies; inadequate technology, inadequate educational training and lack of finance are the major constraints to the development of the small scale design and fabrication industry in Nigeria. Recommendations are made for overcoming these constraints.