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Characterization and technological properties of two clay soils in Republic of Congo

Author Affiliations

  • 1Laboratory of Applied Mineral Chemistry (LACMA), Faculty of Science and Technology, Marien Ngouabi University, Congo and Ecole Normale Supérieure, Marien Ngouabi University, Congo
  • 2Laboratory of Applied Mineral Chemistry (LACMA), Faculty of Science and Technology, Marien Ngouabi University, Congo
  • 3Research Group on Physicochemical and Mineralogical Properties of Materials, Faculty of Sci. and Tech., Marien Ngouabi University, Congo
  • 4Laboratory of Applied Mineral Chemistry (LACMA), Faculty of Science and Technology, Marien Ngouabi University, Congo

Res. J. Material Sci., Volume 7, Issue (1), Pages 1-10, January,16 (2019)


The determination of the physicochemical and mineralogical characteristics as well as the technological properties of two clays used by peasants in the making of fired clay bricks in the Madingou and Makonongo localities respectively in the Bouenza and Pool Departments of Congo-Brazzaville, is the general objective of this work. Particle size distribution and Atterberg limits were measured. X-rays diffraction supplemented by chemical analysis was used to determine the mineralogy of these soils. The water absorption, firing shrinkage and the flexural strength of the bricks made with these two types of soil and baked at different temperatures were measured. The MAD sample is of silty clay texture while the MAKO sample is sandy clay loam texture. These textures have made possible to manufacture fired clay products with these soils as clay. These soils are considered as moderately plastic inorganic clays. These materials have optimum molding properties and the estimated shrinkage is relatively small. X-ray diffraction and chemical analysis indicated that MAD is a kaolinitic clay containing small proportion of illite while MAKO is an illitico-kaolinitic clay with kaolinitic predominance. The iron oxide content associated with the presence of titanium oxide ensures a colored firing. The ternary diagrams taking into account the mineralogical composition and the chemical composition leads us to consider that these soils will give colored bodies. The water absorption obtained (15.53% for MAD and 14.43% for MAKO) indicates that the sherds obtained at 1150°C are porous and favorable for the production of structural ceramics (bricks, tiles, floor coverings, drainage pipes). Since MAD has not reached the optimal sintering temperature at 1150°C, it is possible to find other uses with MAD depending on the technological parameters corresponding to its optimal sintering temperature. With regard to the technological properties it is possible to manufacture ceramic tiles type red monoporosa, red birapida and majolica by making additions of materials containing limestone.


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