High Calcium Fly Ashes are reactive materials that often do not meet the limits of the standards. Therefore, most of the quantity produced annually in the world, due to lignite burning, remains unexploited and charges the environment. Actually, a low percentage of the materials is absorbed at a permanent basis from the cement industry and huge amounts are rejected or used for reclamation of mining areas. However, investigation on these materials has shown which are the weak points and how they could be overcome by using advances in materials technology.