Physico-chemical characterization of thermally treated bentonite

Abstract

Samples of original and thermally treated bentonite at 650°C 4h were characterized with chemical analysis, X-ray diffraction, thermal analysis, mercury porosimetry, differential scanning calorimetry, physisorption measurement and scanning electron microscopy. These consequence of the heating have been found. The chemical analysis shows high silica and alumina contents and small quantities of Fe+3, Ca+2 and Mg+2. XRD analysis shown the presence the main minerals are montmorillonite and opal CT, in the subordinate quantity illite. The result of the heating was the decomposition of clay minerals. Further, the increase in silica and alumina contents. A significant changes in the original pore structure have been found. The changes were characterized by the expressed increase in the content of total porosity caused by the achieved occurence of the pores covering pore radius area over 2000nm. This effect represents the increased openness of the pore structure which may have the significant role in the intensity of alkali-activation process as a factor contributing to the increase of the contact of alkali activator solution with the activated solid. As a possible consequence of the increased openness could be the acceleration of alkali-activation process resulting, for example, in the acceleration of the strength development of binding system based on the thermally treated bentonite.