Clinker-Free Cement: A New Reality

The search for binders with a lower environmental impact has grown, especially for those with reduced clinker content or even for formulations not used due to the high CO2 emissions associated with their production. In this context, the steel industry, which generates a significant amount of waste and co-products, especially steel aggregates, such as blast furnace slag and basic oxygen slag, can be a source of raw materials for cement plants. For this reason, in search of an innovative alternative with low environmental impact, in this work, a clinker-free cement was developed by mixing waste from steel and civil construction. The results of this study demonstrated the possibility of producing a Portland clinker-free cement, using only solid waste, through a mixture of steel slag from blast furnaces, basic oxygen slag and gypsum residue from civil construction, presenting hydraulic properties compatible with national cement CPIII-32 and CPII E-32, and the European cement CSS 32.5 N. The cement mixtures were also characterized as resistant to sulfate attack. It was found that the basic oxygen slag acted as an alkaline activator, thus enhancing the hydration process of the mixture of blast furnace slag and gypsum.