Department of Physics

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    Investigation of mechanical properties of ceramic tiles developed from selected clay deposits in Uganda
    (Kyambogo University [unpublished work], 2023-10) Mukwaya, George William
    In this study the characteristics of Buwambo kaolin, Lunya feldspar, Ntawo ball clay and Liddo beach sand were determined. The Modulus of Rapture (MOR) and Compressive Strength (CS) of the tiles produced using kaolin:feldspar of different composition ratios were determined. The composition ratios of kaolin:feldspar used were 4:3, 3:4, 5:9 and 2:5 by mass. On the other hand, a fixed composition ratio was used for ball clay:sand of 5:1 by mass (Ochen et.al 2012). The samples were fired at 1100 0C for 8 hours. Using the scanning electron microscope (SEM), the Buwambo kaolin had a porous cellular structure of irregular-shaped particles of average size of 0.202 ± 0.131 μm. Liddo beach sand had porous particles with average particle size of 0.168 ± 0.198 μm, the Lunya feldspar had irregular confined particles with average particle size of 0.153 ± 0.105 μm and the Ntawo ball clay had fine grained uniform rounded particles of average size of 0.095 ± 0.055 μm. X-ray fluorescence (XRF) and Energy dispersive x-ray (EDX) spectroscopy were used to determine the elemental composition. The XRF on Liddo beach sand showed that it is mainly composed of 99.5 % SiO2 with trace amounts of Al2O3 and Fe2O3 each 0.2 %. The EDX revealed that Buwambo kaolin mainly had 11.15 % Aluminium and 10.83 % Silicon. The Lunya feldspar mainly had 19.53 % Silicon and 5.46 % Sodium. The Ntawo ball clay mainly had 12.91 % silicon and 4.52 % aluminium. X-ray diffraction (XRD) on Liddo beach sand showed a broad reflection peak at 2θ = 22.86 o indicating its amorphous nature. The Lunya feldspar showed major peaks at 20.69, 26.40 and 29.52 o which are within the acceptable range of sodium feldspar. The Ntawo ball clay showed major peaks at 2θ = 20.82, 26.53 and 27.35 o. For Buwambo kaolin, the major peaks were located at 2θ = 12.29 and 27.40 o. The MOR and CS were significantly dependent on composition ratios at significant levels α = 0.01 and α = 0.05 and therefore the null hypotheses that the CS and MOR of the tiles produced are not affected by the composition ratios of the clay mixture rejected at the two levels of significance. The sample with the highest kaolin-feldspar ratio of 4:3 had the highest MOR of 30.84 ± 2.67 MPa at α = 0.01 and 30.84 ± 1.60 MPa at α = 0.05. It also had the highest CS of 1.36 ± 0.06 MPa at α = 0.01 and 1.36 ± 0.04 MPa at α = 0.05. Similarly, the sample with the lowest kaolin-feldspar ratio of 2:5 had the least MOR of 18.58 ± 0.51 MPa at α = 0.01 and 18.58 ± 0.31 MPa at α = 0.05. It also had the least CS of 0.82 ± 0.03 MPa at α = 0.01 and 0.82 ± 0.02 at α = 0.05. Further investigation should be carried out using other clay deposits to find out how the variation in the amount of kaolin and feldspar in them would affect the CS and MOR of tile samples developed using these clays.