From selective dissolution to crystal chemistry of brownmillerite in sulfate resisting cement

The aim of this study is to extract brownmillerite from sulfate resisting Portland cement (SRPC) in order determine its crystal chemistry and the effects dissolution protocols. Brownmillerites (C4AF) four SRPC were extracted systematically studied by X-ray diffraction (XRD), electron probe microanalysis (EPMA), fluorescence spectroscopy. Two extraction steps used. first salicylic acid/methanol (SAM) protocol that leaves a residue rich ferrite, C3A sulfates. Precipitated hydrated minerals are also observed for clinker with high molar SO3/Na2Oeq ratio. second, developed paper, uses acetic acid (AcA) dissolve Rietveld refinements showed all brownmillerites crystallize Ibm2 space group. families identified their aluminum content cell parameters, related presence clinker. EPMA indicated ferrites SR0 SR3 cements have Al/Fe ratios about 0.7 0.8–1.0, respectively. XRD allows predict (Al+Mg+Si)/Fe ratio good agreement EPMA. SAM best way AcA recommended sulfates further reactivity studies.