Valorization of galvanic sludge in sulfoaluminate cement

Every year increasing amounts of industrial waste are generated worldwide. Depending on their characteristics, wastes can represent an important source of secondary raw materials in order to replace natural resources. In this study, galvanic sludge (LDG) was used as raw material in sulfoaluminate cement. This waste was incorporated to sulfoaluminate cement (CSA), at a weight ratio of 25%, to compose an blended sulfoaluminate cement (BCSA). The compressive strength, drying shrinkage and products of hydration were determined. The efficiency of CSA towards the retention of chromium (the main pollutant present in the sludge) was also investigated. Compressive strength higher than 30 MPa was obtained. The main product of hydration (ettringite) was also identified and the encapsulation of Cr in hydration phases was verified.