Journal de génie civil et environnemental

Agriculture is one of the main economic activities for Kenyans; the wastes from agriculture are minimally used. Among the crops grown in Kenya is the banana and produces about one million tonnes of bananas yearly, mostly for local consumption, of which the banana herb produces the fruits once in a lifetime, thus the stem becomes waste afterward. The waste from the banana plant includes leaves, stems, peduncles, peels, and rejected fruits. The banana waste is organic and thus is suitable for anaerobic digestion in which the solid digestate has suitable nutrients to be used as fertilizer. Batch fermentation at the mesophilic temperature range was carried out in triple determinations, this also applied to the blank sample. After the batch test was complete, the pH of the fermentation residue was measured electrochemically using a pH meter. The COD of the residue (both Solid and liquid) was also determined. Analysis of the biogas produced by gas chromatography enabled the methane part of the gas to be calculated.

At the classical literature of the design of the shell there is used the coordinated system of the middle surfaces of principle curvatures or common non-orthogonal coordinate system. The system of equations of the shells of complex forms is complicated and it’s difficult to receive the analytical decision. For analyses of the shells with non-orthogonal coordinate system and the most shells of complex form in the coordinate system of principle curvatures there is used usually finite element method which usually uses only the equation of the surface but don’t take into account the geometrical characteristics of the middle surfaces of the shell. At the chair of strength of materials and constructions of Engineering Academy RUDN there is worked up the complex program VRMSHELL for analyses of the shells of complex forms by variation-difference method. The complex includes the library of curves on the base of which there are calculated the geometrical characteristics of the classes of the surfaces included at the program complex. The complex includes the classes of surfaces as cylindrical, surfaces of rotation, Joachimsthal’s surfaces, Monge’s surfaces. The coordinate system of surfaces of these classes is the coordinate system of principle curvatures.

The variation-difference method is a convenient numerical method for shells of complex forms. It is enough when only cinematic boundary conditions are satisfied because the method is based on the principle of Lagrange. Another advantage of the variation-difference method is the better opportunity to create computer programs based on it. For shell analysis in orthogonal coordinate system as well as for shell analysis in principal curvatures the system of equations describing stress-strain state can be simplified. In this paper the difference between analysis in orthogonal coordinate system and analysis in principal curvatures of the surface is considered. The main distinction of the analysis of shells in orthogonal curvilinear coordinate system is the necessity of determination of components which include curvature of torsion of coordinate lines. The addition of these components in the equations of the theory of shells for the coordinate system in principal curvatures gives possibility to analyze shells in common orthogonal coordinate system. In this article shell analysis in orthogonal coordinate system is applied to shells based on normal cyclic surfaces.

This research paper summarizes published research works on the suitability of cement as an effective chemical stabilizer to improve the strength and durability requirements of sand to be used as subgrade and base courses for rail track and road construction respectively. Advantages and problems associated with soil stabilization using chemicals have also been briefly discussed in this report. It has been confirmed that ordinary Portland cement is an effective chemical stabilizer to improve both the index and strength properties of soils, however, the optima percentage of cement contents are varied from a soil type to another. In addition, further research has to be carried out as the percentage of cement content varies from region to region and from soil characteristics to another. This is necessary so as to determine the optimum percentage of cement content that would yield the desired subgrade CBR values with some other index properties to meet the specified requirements in any selected design manual.

The manufacturing of cement consumes energy and results carbon dioxide emissions. This work focused on producing cement clinker using coal fly ash (CFA), sewage sludge ash (SSA) and an industrial waste with a high content of calcium silicate (CS). Experiments were conducted to assume the use of a process that may consume less energy and raw materials that used in cement clinker manufacturing. The raw mixtures were prepared with lower clay and limestone contents than those used in Portland clinker manufacturing and then burned at lower temperatures, ranged from 1000 to 1200 °C. Due to the content of fluxes and mineralizers of the raw mixtures, this method could decrease carbon dioxide emissions from calcination up to 60% and energy consumption up to 350 kcal/kg of clinker. The free lime content of the clinker was found out by volumetric analysis and was consistent with free lime content in Portland cement clinker. Activation energies ranged from 42.7 to 91.1 kJ/mol and the cement clinkers contents of fluorine varied from 0.82 to 3.9%. The main characterizations of the obtained clinker, which were X-ray fluorescence, X-ray diffraction and SEM, highlighted interesting composition as building material.

The Journal of Civil and Environmental Engineering (ISSN: 2165-784X) is an international peer-reviewed journal that emphasizes multidisciplinary aspects of environmentally sustainable civil engineering mechanisms, practices, tools and techniques through its open-access platform. The journal represents a platform for the experts and emerging researchers to communicate their scientific knowledge related to fundamentals and advanced methodologies, tools and techniques in civil and environmental engineering.