Recycling steel slag as a cement additive

In Canada, approximately 1 million tonnes of steel slag are produced annually, but, at the present time, there is no economic outlet for the large scale recycling of this by-product. The overall objective of this work was to determine whether steel slag might be processed into a sufficiently cementitious material to allow it to be recycled as an additive to ordinary Portland cement clinker. Blending steel slag with with clinker in a modest ratio of 1:10, it would be possible to effectively recycle all of this steelmaking by-product. Although steel slag has a composition which is similar to that of Portland cement, (consisting mainly of lime, silica, and iron oxide), there are important compositional, mineralogical, and process related differences. Steel slag has limited cementitious properties due to both a lack of tricalcium silicate and the presence of wustite solid solutions as a predominant mineral phase. Even though wustite (FeO) possesses no inherent cementitious properties, it has been shown that hematite (Fe2C