Sulfate resistance of calcium sulphoaluminate cement
Abstract
AbstractThe resistance to chemical sulfate attack was tested for cements containing various amounts of tricalcium aluminate (C3A) and compared to that of calcium sulphoaluminate-belite cement containing no detectable amount of C3A. The six materials tested included a portland Type I (11% C3A), Type II (6% C3A), a Type V (0.5% C3A), and a rapid setting calcium sulphoaluminate (CSA) cement (0% C3A). In addition, two intermediate blends (0.4 and 5.0% C3A) were tested by combining these portland cements with shrinkage compensating CSA cement. Mortar cubes were immersed for two years in a solution containing high concentrations of sodium and sodium/potassium sulfate. Degradation of the mortar cubes was assessed qualitatively via visual observation and quantitatively through measurement of weight change. The magnitude of the degradation by sulfate attack was found to correlate well with C3A content as measured by X-ray diffraction, with Type I portland sustaining the heaviest damage and the CSA rapid setting cement remaining essentially unaffected by the prolonged exposure to the highly sulphated environment.