AUTHOR: OSONWA, NOBERT OKEY (M.ENG.)
DEPARTMENT: Metallurgical and Material Engineering
SCHOOL: School of Engineering and Engineering Technology (SEET)
AFFILIATION: Federal University of Technology Owerri (FUTO)
The effects of particle size and particle size distributions of three clay samples, on their modulus of rupture were studied. The three clay samples were collected from natural clay deposits at Nsu; Ohiya-Umuahia; and Awo-Omamma all in south eastern Nigeria. The particle size analysis of the clay samples was done by laser diffraction in wet suspension mode and the results disclosed that Awo-Omamma clay has greater proportion of the larger sized particles, (21μm -25μm) and (25μm -51μm), than Ohiya clay and Nsu clay. Also the three clay samples have volume mean diameters (VMD) of 6.56μm, 8.93μm and 11.29μm for Nsu clay, Ohiya clay and Awo-Omamma clay respectively.The moduliof rupture of the clay samples were also determined for the green state as well as when fired to 900°C and 1100°C. Other thermo-physical parameters of the clay samples such as porosity; shrinkage and bulk density were also determined. The modulus of rupture of Awo-Omamma clay was 0.183N/mm2for the green state, 0.426N/mm2when fired at 900°C and 0.544N/mm2when fired at 1100°C. These values were quite low when compared to 0.369N/mm2and 0.569N/mm2dry modulus of rupture values for Nsu and Ohiya clays respectively. Nsu and Ohiya clays also have superior mechanical behaviour when fired as indicated by the modulus of rupture values of 1.04N/mm2; at 900°C and 1.51N/mm2at 1100°C for Nsu clay, and 1.35N/mm2at 900°C and 1.53N/mm2at 1100°C for Ohiya clay. Comparison of the modulus of rupture of the three clay samples with their particle size distributions revealed that a high proportion of the larger sized particles, (21μm -51μm) will lower the modulus of rupture of the clay. The proportions of this particle size range contained by the three clay samples are 16.14% for Awo-Omamma, 6.65% for Ohiya and 4.05% for Nsu clay.
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