Mineralogical, physico-chemical and ceramic properties of clay materials from Sekandé and Gashiga (North, Cameroon) and their suitability in earthenware production

Clayey materials from Sekandé and Gashiga localities in the northern part in Cameroon traditionally used for pottery were studied. Eight samples were collected and investigated by XRD, IR, XRF, physical and firing properties from 900, 1000 and 1100 °C. In term of mineralogy, studied clays are rich in smectites, illite, kaolinite, quartz, feldspar and mica. Physicochemically, results show large particle size variations with high plasticity (18–30%). Clay fraction (<2 μm) ranges from 18 to 38% and sand fraction from 40 to 53%. Si0(2) (46–55%) and Al(2)O(3) (19–21%) are major chemicals oxides, followed by Fe(2)O(3) (6.68–10.82%) and alcali and alcali-earth elements (8–10%). These characteristics govern their behavior on firing with temperature development. The color of specimens was predominantly red after firing. Between 900 and 1100 °C, their color ranged from reddish brown, red yellow or brown red to red. The linear shrinkage values vary from 0.5% to 7%, weight loss from 4% to 9% and bulk density from 1.74 to 2.21 g/m(3). These values increased gradually for specimens fired from 900 to 1100 °C. The water absorption decreased from 17% to 14%. The evaluation of the studied clays based on their mineralogical, physicochemical and ceramic properties revealed that they are suitable for the manufacture of earthenware products like fired bricks.