Per: valber domingos pinheiro (UENF - ALBERTO LAMEG), RAMON FERNANDES DE ABREU (UENF), gustavo dos santos oliveira (uenf), diogo souza santos (uenf), Afonso Rangel Garcez de Azevedo (uenf), Jonas Alexandre (uenf)
Abstract:
In civil construction, clays with different mineralogies are used, the kaolinitic clays having the greatest potential for applicability in Supplementary Cementitious Materials to replace Portland cement. In this study, a kaolinitic clay was characterized and its main properties were evaluated when submitted to thermal calcination treatment at different temperatures. The calcination process was carried out at gradual temperatures in order to assess the extension of plasticity limits, its thermal behavior and pozzolanic activity. The clay was characterized as to its chemical composition by X-ray fluorescence spectrometry, mineralogical analysis by X-ray diffraction, plasticity limits by Casagrande, particle size distribution by sedimentation, thermogravimetric analysis, and pozzolanic activity by means of the electrical conductivity test and Modified Chapelle. In this context a plasticity decay was observed according to the temperature increase of the proposed thermal treatment. The chemical and mineralogical characterizations showed high silica and alumina content as well as the presence of kaolinite in the sample. The thermal analysis pointed out that the amorphization of the main soil mineral occurred between the temperatures 400°C and 500°C with the dehydroxylation of kaolinite to the metakaolinite phase. The pozzolanic analysis of the material indicated an increase in pozzolanic activity until the temperature of 600°C.