This part of the research explored the reaction of  hybrid alkaline cements when they are exposed to acid (0.1-N HCl), sulphates and seawater. The hybrid cement used in the experiments comprised essentially metallurgical slag generated by the Fe and Zn industries. A standard Portland cement was used as the reference system. The findings showed that performance of  these hybrid cements was similar to the results observed for the control. In a subsequent industrial trial, the concrete made with this experimental binder was successfully used in the manufacture of precast blocks and pavers.