Mineralogical evolution of artificial aggregates manufactured with different iron phases

A selection of fifty-one artificial aggregates, manufactured with different proportions of kaolinite, an iron phase (Fe⁰, Fe₂O₃, Fe₃O₄ or FeS₂), cork powder and sodium carbonate in three previous works, have been studied mineralogically using the quantitative Rietveld XRD method. Comparisons between the mineral percentage in the raw materials and the phase percentage in the aggregate have been carried out. Additionally, independence contrast tests have been conducted to determine if significant relationships exist between the raw material mineralogical composition and the aggregate phase composition. Based on these statistical results, the mineralogical evolution, the possible reactions that may have taken place and the type of atmosphere required for them have been presented. Mullite, metallic iron, cristobalite, hematite, magnetite, hercynite, fayalite, clinopyroxenes, troilite, nepheline and amorphous material were new phases produced in the aggregates. The presence and/or percentage of the majority of them were greatly influenced by the added iron phase and by the type of atmosphere in the aggregates.