Solidification/stabilization of a tannery waste with blended cement and Wyoming bentonite

The solidification/stabilization of a tannery waste, which has a high chrom ium content, was studied by thermogravimetry (TG), derivative thermogravime try (DTG) and differential thermal analysis (DTA). Pastes prepared with wat er, cement, tannery waste and Wyoming bentonite were analyzed after differe nt setting times during the first 28 days of solidification. In the present work it is clear that Wyoming bentonite combined with waste affects cement hydration, while bentonite alone does not affect it significantly. The pre sence of the waste results in a small acceleration of the cement hydration reactions, probably due to the presence of extra Ca and alkalinity in the w aste. When waste is present in the sample during TG and DTG analysis, it is burned to carbon dioxide, which partially reacts with the calcium hydroxid e formed during cement hydration. This results in an underestimate of the c alcium hydroxide content of the solidified sample. The greater the degree o f hydration of the waste-containing cement sample, the greater the amount o f carbon dioxide absorbed.