Properties of two ceramic products of kaloinite clays from western Cameroon

Two clay materials (one kaolinite and the other halloysite) from the western province of Cameroon were studied in order to use them in ceramic industries. Cylindrical samples were made up from the clay bodies and subjected to a thermal treatment ranging from 1000 to 1450degreesC; the following characteristics were examined: bulk density, apparent porosity, linear shrinkage, compressive strength as well as the cristalline phases which appear in the treated materials. Ceramics obtained from kaolinitic material have lower apparent porosity, higher bulk density and a greater compressive strength, at least up to 1250degreesC. Ceramics from halloysitic clay remain porous enough. The two materials can be used to manufacture terracotta products. The kaolinitic. material can serve in producing stoneware fragments while halloysitic clay, after confirmation of its pyrometric resistance, can be used as alumino-silicate refractory above 1400degreesC.