Phase profiling of carbonation-cured calcium sulfoaluminate cements

Abstract

The present study investigated the effect of $CO_2$ concentration during carbonation curing on the microstructural evolution of calcium sulfoaluminate cements. Carbonation curing was performed for 28 days at 3% and 10% $CO_2$ concentrations. To profile the microstructural phase behavior within the cement composite, samples were collected from the surface of the composite to a depth of 30 mm at every specific curing day. Different $CO_2$ concentrations induced significant changes in the formation behavior of calcium carbonate polymorphs. At 3% $CO_2$ concentration, vaterite and aragonite were mainly observed, and calcite was generated due to the recrystallization of vaterite. At 10% $CO_2$ concentration, the formation of aragonite was found to be predominant, and a phase transition from vaterite to aragonite was distinctly observed with increasing curing periods. Carbonation curing promoted the formation of stra ̈tlingite, as calcium carbonates provide a nucleation site to shorten the induction period of belite.