Use of oxygen steelmaking slag to obtain clinker: experimental study in laboratory scale and hydration characterization in the first ages

摘要

For some time now steelmaking slag has been employed as a substitution of hematite and bauxite in clinker production. As it has calcium oxide in its composition the the quantities of limestoneconsumed in its production could, consequently, be reduced. This work presents the characterization of two cements produced by clinkers obtained with steel slag. One of the clinkers was composed of a blend of a modified oxygen steelmaking slag by pyrometalurgical process and in natura oxygen steelmaking slag. The other one was composed only of in natura oxygen steelmaking slag. A rotative high temperature pilot scale furnace was applied to produce clinker and cement in enough quantities for chemical, mineralogical, physical and mechanical characterizations. Chemical analysis reflected light microscopy and quantitative mineralogical XRD analysis using Rietveld method and were applied in clinker characterization. The physical-mechanical characterizations of cements were done after the addition of gypsum in clinkers. Furthermore, the cement hydration was analyzed by means of isothermal calorimetry, thermogravimetry and X-ray diffraction in cement paste. The chemical compositions of clinkers are similar. Regarding the clinker phases, the C3S and C3A contents determined by Rietveld method were lower than those estimated by Bogue. In the case of C2S and C4AF contents the values were higher. Compressive strengths of cements were satisfactory when compared with ordinary Portland cement. The combination of techniques for the characterizations represents an effective contribution to understand the behavior of these non-conventional cements and motivate producers to re-evaluate the common quality control currently applied by clinker and cement manufacturers and users.