Browsing by Author "Salman, Ash-Shu'ara"

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    Impact of treatment temperature of metakaolin on strength and sulfate resistance of concrete
    (Research on Engineering Structures and Materials, 2024-02-05) Akinpelu, Mutiu; Salman, Ash-Shu'ara; Jimoh, Yusuf
    Calcined clay, a widely studied supplementary cementitious material, has shown positive impacts on concrete's microstructural properties, strength development, and durability. The variation in raw clay mineral concentration across different locations influences the optimal calcination temperature needed to activate its pozzolanic reactivity. This investigation focuses on studying the effects of calcination temperature on the characterization and pozzolanic reactivity of Nigerian Kaolinite clay. The clay was calcined at temperatures ranging from 600˚C to 900˚C for 2 hours. Characterization involved X-ray Diffraction (XRD), X-ray Fluorescence (XRF), and Scanning Electron Microscope (SEM) analyses. Blended mixtures, incorporating 10%, 20%, 30%, and 40% metakaolin as cement replacement, were assessed for workability, strength, and durability properties at 7, 14, 28, and 56 days to determine the clay's pozzolanic reactivity. XRF categorized the metakaolin as a class N pozzolan, while XRD indicated that 800˚C for 2 hours was necessary for complete dihydroxylation. Compressive, tensile, and sulfate resistance tests confirmed that treating the clay at 800˚C for 2 hours optimized its performance. The mix with 10% metakaolin outperformed the control by 6.4%, 14.7%, and 14.1% in compressive strength at 14th, 28th, and 56th days, respectively. While the best performance was at 10% replacement, levels up to 30% also demonstrated satisfactory results compared to the control, showing potential for achieving desired strengths. Linear regression models were also developed to establish the relationship between compressive and split tensile strengths across curing periods. The resulting equations demonstrate excellent predictive performance with correlation coefficients ranging from 0.928 to 0.991.
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    Numerical study on the effect of different column shapes on punching shear behavior of flat slabs
    (Elsevier, 2023-08-15) Akinpelu, Mutiu; Salman, Ash-Shu'ara
    This study was carried out to assess the punching shear behavior of flat slabs considering the use of various column shapes such as L, T, and Cruciform as support. The flat slab floor system is becoming most adopted in various structures ranging from medium-rise to skyscrapers, garages, factories, airports, etc. Although in this field of study, various research has been carried out over the decade, limited considerations were made for compound column geometries. Finite Element modelling software Abaqus was used in the development of a numerical model capable of predicting punching shear features of flat slabs. The control model was a flat slab supported on a square column established from an experimental test reported in previously published literature. The concrete material behavior was defined in the Concrete Damage Plasticity Model and the best-suited parameters were deduced by sensitivity analysis. A comparative analysis was performed to compare the numerical results to both experimental and code predictions from ACI 318-19, Eurocode 2, 2004 and Model Code 2010. The study revealed that the shape of columns influences the punching shear capacity, with L, T, and Cruciform giving an increase of 3%, 5.2% and 22.6% respectively.