Effect of BaCO3 reactivity and mixing procedure on sulfate-resistant cement performance

Abstract

The present study focuses on exploring the effects of reactivity and degree of dispersion of BaCO additions in the manufacture of sulfate-resistant OPC cements. A new electrochemical deposition method is attempted to effectively disperse BaCO particles (studying two different materials with particle size: D = 11.45 and 2.37 μm) on cement to enhance their reactivity and favour sulfate immobilisation in the form of BaSO. The barium carbonate additions, particularly the finest, activate cement hydration to a greater extent. Electrodeposition is also observed to improve early age reactivity (2 d–7 d) in fine BaCO. Cement paste bearing 15 wt % BaCO is more resistant to sulfate attack by a 5% (w/v) solution of NaSO (180 d at 23 °C) than a commercial sulfate-resistant cement, although secondary ettringite and gypsum precipitated in all cases.