Masters Degree Dissertations

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Browsing Masters Degree Dissertations by Subject "Concrete"

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    Compressive strength of concrete produced using aggregates from selected types of rocks in Uganda
    (Kyambogo university (Unpublished work), 2024-05) Kawiso, Micah
    This study was on determining the compressive strength of concrete made of granite, quartzite and sandstone aggregates of three aggregate sizes of 6.3 mm, 10 mm, and 14 mm and using three cement, sand and aggregate mixture ratios of 1:3:6, 1:2:4, and 1:1:2. This was to find out the effects of mixture ratios, aggregate sizes and aggregate types on compressive strength of the concrete. The samples of concrete were cured for 14 days and then a compression test machine was used to determine the compressive strength of the samples. The average compressive strength of granite concrete of mixture ratios 1:3:6, 1:2:4 and 1:1:2 were 8.56, 19.10 and 32.59 MPa respectively. The mean compressive strength of quartzite concrete of mixture ratios 1:3:6, 1:2:4 and 1:1:2 were 8.78, 17.57 and 31.22 MPa respectively. The average compressive strength of sandstone concrete of mixture ratios 1:3:6, 1:2:4 and 1:1:2 were 9.71, 20.75 and 33.58 MPa respectively. The mean compressive strength of granite concrete of aggregate sizes 6.3, 10, and 14 mm were 18.77, 19.62, and 21.87 MPa respectively. The mean compressive strength of quartzite concrete of aggregate sizes 6.3, 10, and 14 mm were 17.93, 18.95, 20.71 MPa respectively. The mean compressive strength of sandstone concrete of aggregate sizes 6.3, 10, and 14 mm were 19.49, 21.01, 23.21 MPa respectively. The results have revealed that the compressive strength of granite, quartzite and sandstone concrete increased with increase in cement aggregate ratio. Mixture ratio 1:1:2 produced the highest compressive strength of concrete and mixture ratio 1:3:6 produced the lowest compressive strength of concrete. The results have further revealed that compressive strength of the three rock types increased with increase in size of aggregate. The difference in the compressive strength for the three different types of rocks was negligible. Therefore, mixture ratios and aggregate sizes affect concrete compressive strength but rock types used did not affect the compressive strength of concrete samples. Builders and engineers who wish to construct structures should mind most about the aggregate size and mixture ratio than the granite, quartzite or sandstone aggregates used.
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    Investigation of mechanical properties of concrete developed from a binder composite of sugar cane bagasse ash and Portland cement
    (Kyambogo University (Unpublished work), 2024-10) Nzugua, Michael Evans
    Cement production has been growing over time. Statistics indicate more growth as the human population increases. However, cement production relies on natural resources such as limestone rocks. The mining of these minerals poses grave environmental hazards. Increased limestone mining and its use in cement production have led to, deforestation, soil and water contamination and greenhouse gas (GHG) emissions mostly carbon dioxide (CO2). This has led to global warming and the rising of sea levels. The East Africa Community (EAC) countries have immense sugarcane cane bagasse ash (SCBA) which remains unexploited as a supplementary-cementitious material (SCM). This study delved into using EAC SCBA as a pozzolan. SCBA investigated was collected from Kenya's coastal area. Raw SCBA, processed SCBA, Portland cement (PC) and the developed concrete were characterised by various techniques to determine the surface morphology, chemical composition, structural properties and mineralogical composition. The raw SCBA was calcinated at 600 oC to get processed SCBA (SCBA-600). SCBA-600 was then used to design the concrete mix. PC was replaced from 0 to 30 % in steps of 10 %. The flexural and compressive strengths were determined in the hardened state after twenty-eight days of concrete curing. The compressive and flexural strength of the mix containing 20 % SCBA was higher than the control mix by 9.65 and 6.51 %, respectively. The microstructural properties of the developed concrete revealed dense particle distribution, indicating good micro/nanofiller effects of the interfacial transition zone. The processed SCBA was found to meet class N and F of natural pozzolan as per ASTM –C 618. The samples were analysed using XRD, SEM, EDX, and XRF techniques. The concrete design was done following IS 10262-2009 and IS 456. The casting and curing were done as per ASTM C-192 and lastly, the mechanical strengths were done as per ASTM C-39 and ASTM C78-00 standards specifications. These positive results from the experimental investigation, technically portray the Kenya coastal SCBA as a potential SCM.