Contribution à la caractérisation et à la valorisation des argiles du Crétacé inferieur du nord et de la Tunisie

Abstract

The present paper aims at investigating a characterization and valorisation of local clays

collected from North East of Tunisia (Early Cretaceous clays in Ariana, Grombalia and Enfidha areas)

for their application in the ceramics field. Indeed, geological, mineralogical, physicochemical,

technological and ceramic properties of crude samples are studied. Geological investigation is based

on the recognition of Early Cretaceous stratigraphysequences containing clays materials and the

realization of lithostratigraphic columns showing wideargillaceous levels. Mineralogical analysis by

XRD of argillaceous samples shows that Early Cretaceous clays are primarily made up of illite,

kaolinite, interstratified illite-smectite (I-Sm), with a little smectite and chlorite. The associated minerals

are quartz, calcite and feldspar. The studies were carried out with three clay representative clay

mixtures characteristic of these three layers. Physicochemical characterization shows the rates of

major chemical elements, the content of CaCO3 (calcimetry) and the determination of several

properties (cationic exchange capacity (C.E.C), specific surface (S.S), apparent density, permeability,

porosity, pH, salinity, rates of organic matter and organic carbon total). The technological study is

based on the granulometry analysis, the study of plasticity degrees of these clays, the tracing of

Bigot's curves and dilatometer curves. Semi-Industrialtests of manufacture of ceramic biscuits were

carried out on a mixture representative of each studied argillaceous level. The analyses after cooking

showed that the majority of the mixtures have a good result with the temperature of cooking about

1000˚C. Finally, this study reveals that the majority of Early Cretaceous clays in North East of Tunisia

can be used in manufacture of ceramic products.