Engineering
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- ItemEnhanced local contractor participation in the Zambian water supply and sanitation sub-sector.(The University of Zambia., 2024) Katotobwe, Chanda A.B.Water supply and sanitation (WSS) construction projects involve the construction of specialized infrastructure such as water treatment plants, pumping stations, pipelines, reservoirs, and sewage treatment facilities. These type of construction projects present unique technical, regulatory, and societal challenges, often executed by foreign contractors in developing countries like Zambia, with limited local participation. This disparity sparks debates on dependency and sustainability. Existing theories insufficiently address this issue. The overarching research inquiry investigates the dynamics surrounding the low dominance of local contractors in executing WSS projects in Zambia. Additionally, the study delves into the primary barriers confronting local contractor participation in Zambia as they compete for and secure contracts within WSS projects. Employing a Straussian Grounded Theory methodology, the study developed thick descriptors for the underlying issues explaining local contractor participation (LCP) in the WSS sector, which led to the development of theory and a framework advocating for enhanced LCP. Initially, a variety of emerging issue clusters and their corresponding phenomena were delineated and categorized into thematic descriptors. These encompassed clusters relating to procurement and taxation, funding sources, constraints on plant and equipment resources, specialized financial support, contractor technical capacity, governmental capacity building efforts, and regulatory enforcement. Based on these identified issue categories and their observed phenomena, an LCP theory was introduced as a primary contribution of the study within the theoretical proposition framework. This theory encapsulated the theoretical propositions and strategies advocating for enhanced LCP. It posited that a comprehensive approach, tax incentives, affirmative procurement actions, and specialized financial support, could significantly enhance the involvement and competitiveness of local contractors, particularly in the construction industry, specifically within the WSS sector. Tax incentives and leniency policies reduce financial burdens on local contractors, allowing for reinvestment in business growth and improved financial stability. Simultaneously, affirmative actions in procurement ensure equitable competition, levelling the playing field against larger foreign competitors and addressing inherent disadvantages. Furthermore, integrating specialized financial support tailored to the unique needs of local contractors within the sector addresses financial barriers and facilitates their participation in projects. Following the consequential phenomena and strategies upon which these theories were based, holistic strategies and reforms associated with these three theoretical propositions included: revamping taxation policies and procurement practices; diversifying funding sources for sustainable growth; creating equitable opportunities through procurement strategies; establishing specialized financial support institutions; establishing specialized financial support institutions; strengthening policy frameworks and enforcement mechanisms; bridging the knowledge gap for local contractors; mitigating political interference for fair competition; and enhancing government capacity building initiatives. The study advocates for policy, legal and institutional restructuring based on this theory to enhance local contractor participation in WSS projects in Zambia and other developing countries.
- ItemStudy on compressive, tensile and bond properties of used tire rubber reinforced concrete.(The University of Zambia, 2021) Bwalya, TheresaConcrete is one of the most widely used construction material in the world and the construction industry is looking for ways of making concrete using greener methods so as to reduce ecological effects on the environment that come as a result of large scale exploitation of natural aggregates. The construction industry is also in need of finding cost-effective materials to enhance the properties of concrete. Cement and aggregate, which are the major constituents in concrete production are the vital materials needed in the construction industry. This has inevitably led to a continuous and increasing exploitation of natural materials to produce the constituents for concrete production. The result has been the depletion of virgin raw materials and increased effects of environmental degradation. Parallel to the need for the utilization of the natural resources emerges a growing demand to protect the environment and preserve natural resources such as the aggregates and stone for cement production, by use of alternative materials such as recycled or waste materials. In this research, a study was carried out on the use of recycled rubber tyres as a partial replacement for coarse aggregates in concrete production. Recycled waste tyre rubber is a promising material in the construction industry due to its reduced weight, elasticity, energy absorption, sound and heat insulating properties. However, literature suggests that there is a significant loss in the strength of rubberized concrete with increasing tyre content. Further, workability and bond properties have been reported to reduce as well. Therefore, it is necessary to lower or control this loss of strength and other parameters in concrete in the replacement process of natural aggregates. This research aimed at studying the compressive, tensile and bond properties of used tyre rubber reinforced concrete. The research also aimed at establishing whether the use of rubber reinforced concrete (rubberized concrete) is technically and economically viable in Zambia. Rubber modified concrete was compared to normal concrete produced from natural coarse aggregates and Portland cement. The research involved literature review, laboratory testing on natural raw materials and used rubber as aggregates (to determine their properties and suitability for use in concrete), concrete mix design, concrete trial mixes, and tests on both wet and hardened concrete. Test results from laboratory experiments enabled determination of mechanical, physical and durability properties, as well as establishment of the extent of substitution of normal aggregates with waste rubber as aggregate in concrete production. Three classes of concrete, C15, C20 and C25 were produced by substitution of selected percentages of aggrgates by treated chopped waste tire rubber. The chopped rubber, whose surfaces were first roughened by use a wire brush, was later soaked in clean water and then left to dry completely in the sun. This was done to increase the inter-phase bonding between the rubber particles and cement. The percentage replacement of coarse aggregates was 5, 15 and 25 per cent. The size of the chopped rubber aggregates varied from 20 mm to 19 mm. Slump, permeability and bulk density tests were conducted on fresh concrete mixes for both the normal and treated rubber modified concrete. Similarly, compressive strength, tensile splitting strength, bond test and durability against acid attack tests were conducted on hardened concrete. The research established that rubber modified concrete compares favourably with standard concrete, with up to 15 per cent replacement of coarse aggregate. At 15 per cent replacement, only 0.1 per cent loss of strength was established. There was observed reduction in properties with 25 per cent replacement. Rubber modified concrete performed better by gradual cracking at elevated temperatures. There is potential for rubber modified concrete products in Zambia which in turn mitigates adverse impacts resulting from over exploitation of natural aggregates and disposal of used rubber tires.
- ItemFinite element modelling of ultra high performance fibre reinforced concrete beams exposed to fire.(The University of Zambia., 2021) Simwanda, LenganjiA number of research concerns have arisen in the concrete research community on the fire resistance of Ultra-High Performance Fibre Reinforced Concrete (UHPFRC) beams, despite their improved mechanical properties at ambient temperature. The traditional experimental approach to performance-based fire resistance estimation comes with a lot of economic and physical constraints. The recent improvements in both computational power and algorithms suggest that a numerical approach to performance-based fire resistance estimation has the capability to solve some of these challenges. By building on the principle of the finite element method, in this study, finite element models of UHPFRC beams exposed to elevated temperatures in a fire were developed in a finite element software package ABAQUS. The developed finite element models were validated against experimental results reported in a previous experimental study on UHPFRC beams which were pre-loaded under load ratios of 0.2, 0.4 and 0.6 then subjected to 60-minutes ISO 834 fire in a furnace. The finite element model predicted the thermal and mechanical responses of UHPFRC beams which were in good agreement with results reported on the experimental beams. Subsequently, the finite element models were used in a parametric study to investigate the fire resistance of UHPFRC beams under nine different load ratios (0.1-0.9) and different heating regimes, that is, the ISO 834, and the hydrocarbon temperature-time curves and fire resistance ratings were estimated at 0, 30 or 60-minutes for the beams considered. It is hoped that the proposed finite element models be used directly for performance-based fire safety design of UHPFRC beams as a cost-effective numerical tool and be employed in parametric studies to develop simple prescriptive design rules.
- ItemDetermining physical - chemical properties of Zambian soils used as plaster paste - Luapula.(The University of Zambia, 2019) Mulenga, Brian ChilesheSoil plaster pastes have been used around the world by local rural populations for centuries to give a finishing touch to their houses, and depending on the soil used, some chemical contamination cannot be ruled out. Some soils may contain heavy metals and other parameters depending on where it is located and the type of environment. The purpose of this study is to determine the physical and chemical properties in the abundant Zambian coloured soils found in Luapula Province, Mwansabombwe area in Kawambwa District that are used for plastering houses mainly by rural communities. Similar types of soil are found in many other areas around the country. The presence of heavy metals and other parameters could affect the soil colour if binders are added in order to improve these plaster pastes. Analysis of the soil samples was as follows: The pH meter with combined electrode and saturated potassium chloride (KCl) was used to analyze for pH; while for all heavy metals i.e. copper, iron, manganese and chromium, a laboratory protocol of sample digestion analysis for ore and soil was used. Organic content was analyzed by the Walkley Black method involving the reduction of potassium dichromate by the organic carbon compound. Barium sulfate precipitation was used for sulfates and chlorides in titration. Traces of heavy metals found averaged as follows: Copper in all the six samples was 20%, Iron in all the six samples was 0.5395 %% , Chromium in all the six samples was 0.002% , Manganese in all the six samples was 16.17 % respectively. While Organic matter in all the six samples was 18.47 ppm, Chlorides in all the six samples was 11.76 ppm, Sulfates in all the six samples was 10.26 ppm, pH in all the six samples was 5.62 Traces of heavy metals: manganese, iron copper and chromium including parameters: pH, organic matter, sulfates and the chlorides were found in the soil samples. Signifying that, an addition of a binder may trigger a reaction that may alter the original natural colour of the soil. If soil colour is lost then, the desired results of improving the soil paste for use in the construction industry as a plastering material is defeated.
- ItemDetermining Zambia’s potential for bioethanol production as a motor vehicle fuel to meet climate objectives by 2040.(The University of Zambia, 2019) Mwanakaba, Cosmas S.Zambia’s transport sector is driven by imported and costly fossil fuels. Apart from the cost element, fossil fuels are finite. The source is depleting as it is being extracted continuously. Fossil fuels are also pollutants to environment. They contribute 70% of global carbon monoxide (CO) and 19% of global carbon dioxide (CO2) emissions. These levels of emissions contribute to the global greenhouse gasses challenge. The greenhouse gasses are causing unpredictable weather patterns which have affected the agro business and general economic planning. This research looked at bioethanol as an alternative to gasoline in trying to mitigate the challenges highlighted in depending on fossil fuels for the transport sector. The research investigated three locally produced feedstocks namely sweet potato, cassava and sugarcane. The raw data for these crops was gathered at national level. These feedstocks were quantified and converted to bioethanol using appropriate mathematical ratios. The period of assessment ranged from 2007 to 2017 and then forecast to 2040 which is seemingly a global benchmark to migrate from use of fossil fuels to alternative fuel sources preferably biofuels. As at 2018, Zambia was consuming 1.3 million liters of gasoline per day. Historical data showed gradual increases year by year from 2007 to 2017. Interestingly, when the total yields of sugarcane at Zambia Sugar (Nakambala), Kafue Sugar and Kasama Sugar as well as those of the national yields of sweet potato and cassava were converted to bioethanol, the results showed that quantities were moving in tandem up to 2023 with those of gasoline consumed and the curve separated thereafter due to the influence of the trend. The two tables compiled thus the total national gasoline consumption in 2007 was 165,040,279 liters while the converted bioethanol potential from all the feedstocks in the same year was 215,046,582. As at 2017, the national gasoline consumption was 461,427,680 liters while the converted bioethanol potential stood at 561, 419, 763.7 liters without considering the food requirements of the country. The other scenario of the research considered the food requirements of the country and the results as at 2007 for bioethanol potential was 45,173,085 and by 2017 the bioethanol potential was 113, 485,818. This research established that only quantities equivalent to the current yields of sugarcane, cassava and sweet potato (561,419,763.7 liters of bioethanol for 2017 potential) would suffice when converted to bioethanol to replace gasoline as a motor vehicle fuel. The research also established that after forecasting both bioethanol curves trailed lower than that of national gasoline consumption due to irregular increases on the bioethanol results with scenario number two curve moving at the same pace up to 2023 in magnitude and lost momentum thereafter to that of gasoline while scenario number one curve lied almost at bottom of the figure. The levelised cost of energy of all the feedstocks was calculated with molasses being most competitive at $ 0.039/liter followed by cassava at $ 0.062/liter, sugarcane at $ 0.068/liter and sweet potato at $ 0.304/liter