Characterization and use of clays and argillites from the south of Santa Catarina State, Brazil, for the manufacture of clay ceramics

Six clays from various deposits were studied for their use in the production of structural clay products. The clays were characterized using chemical (X-ray fluorescence), mineralogical (X-ray diffraction) and thermal (differential scanning calorimetry/thermogravimetry) analyses. Particle-size distribution was determined by laser diffraction, plasticity by the Pfefferkorn method and the residue by the sieve-size method. Next, specimens were formed by extrusion and characterized by their linear thermal shrinkage (on drying and firing), water absorption, bulk density, porosity and compressive strength. The clays were, in general, suitable for the manufacture of structural ceramics, mainly bricks. The clays from flooded pits (AV1 and AV2) were classified as floodplain clays and alluvial clays. The clays mined in mountainous regions (AM1 and AM2, as well as AV1) were characterized as siliceous clays due to the abundance of free SiO2 phases.