The Effect of Different Bentonites on Cement Hydration During Solidification/Stabilization of Tannery Wastes

Abstract

In the present work, a Portland cement blended with calcium carbonate is being used to study the solidification/stabilization (S/S) of a Brazilian tanning waste arising from leather production. Chromium is the element of greatest concern in this waste, but the waste also contains a residual organic material. Using thermogravimetry (TG) and derivative thermogravimetry (DTG) to identify and quantify the main hydrated phases present in the pastes, this paper presents a comparative study between the effects of Wyoming and Organophilic bentonites (B and OB) on cement hydration. Samples containing combinations of cement, B, OB and waste have been subjected to thermal analysis after different setting times during the first 28 days of the waste S/S process. Both bentonites affect the cement hydration, with no significant differences in hydration degree after 1 week. This work shows further examples of the great utility of thermal analysis techniques in the study of very complex systems containing both crystalline and amorphous mineral materials as well as organics.