Avalia？？o de argilas cauliníticas de Campos dos Goytacazes utilizadas para fabrica？？o de ceramica vermelha

this work has for objective to evaluate the effect of the variation, in the ceramic body composition, of the two main types of clays from campos dos goytacazes north of the state of rio de janeiro, in the processing and technical performance of the red ceramic. the clays designated as "strong" and "weak" were previously submitted to mineralogical, chemical and physical characterization tests. in the sequence, compositions were prepared varying the amount of the clays. the plasticity of the clays was determined by the atterberg method. specimens were prepared by uniaxial pressing at 20 mpa before firing at 900 oc. the technological properties evaluates were: linear shrinkage, water absorption and flexural strength. the results showed that the clays are mineralogically similar with the presence of kaolinite, quartz, gibbsite and muscovite mica. the "weak" clay significantly decreases the water absorption and the firing linear shrinkage of the compositions. however, it was also observed a decrease in the mechanical strength. this behavior is due to the presence of quartz in a higher amount.