Identification and traditional ceramic application of clays from the Chouamekh region in south-eastern Tunisia

• The mineralogical, chemical and geotechnical characterization of the Tunisian clays
• The firing behavior of the Tunisian clays
• The ceramic application of the Tunisian clays

For the first time, Permo-Triassic clays collected from the Chouamekh region in south-eastern Tunisia have been studied for their possible use in the ceramic industry. In terms of mineralogy, they can be considered illitic clays. However, other clay minerals, such as kaolinite, I/Sm mixed-layer and chlorite are also present. The chemical analysis indicates that these clays are notably siliceous. The alkali content (K2O + Na2O) is high (~ 4.2%), thus explaining why these clays can be fired at relatively low temperatures. The amount of alumina and iron oxide, with an average of 15% and 6.3% respectively, is variable. The tests show that these clays have low to medium plasticity values (PI = 11–28%). The firing shrinkage and the expansion are limited. A lower firing and drying temperature can be translated into significant energy savings. Technical tests show that the properties fall within the ceramic International Standards (ISO). Ceramic tiles and bricks prepared from these clays have suitable characteristics without defects and can be classified in group BIII according to the European Standard NF EN159 (1991).