Alternative inorganic binders based on alkali-activated metallurgical slags

Alkali-activation technology has been used to produce inorganic cements for over a century, as a means of valorizing wastes or industrial by-products derived from different commercial activities. Granulated blast furnace slags (GBFS), derived from the iron-making industry, have been widely utilized for the production of alkali-activated cements. Significant advances in understanding the roles of different factors which govern the properties of alkali-activated GBFS cements have been made in recent decades, to the point that concretes based on alkali-activated GBFS are commercially deployed in several parts of the world. However, GBFS is not the only slag that can be used as a raw material for producing Portland clinker-free inorganic binders. Various other metallurgical slags, which currently have little or no commercial value, can also be utilized as raw materials for producing inorganic cements. The main difficulty to overcome in this area is the generally lower hydraulic reactivity of these slags compared with GBFS, and the high content of heavy metals which can limit the utilization of some such slags as building materials. Alkali-activation can thus, in some instances, also be seen as a means for the consolidation and safe disposal of such materials, which may otherwise pose an environmental hazard. This chapter provides an overview of inorganic cements produced via alkali-activation, particularly those which utilize nonblast furnace metallurgical slags including steel, ferronickel, titaniferous, stainless steel, lead, copper, zinc, nickel, manganese, silicomanganese, and phosphorus slags.