Prediction of Sulfate Attack Products in Portland-Limestone Cements: The Effect of Cation Type and Concentration

Abstract

Portland-limestone cement materials are susceptible to sulfate attack at low temperature and high humidity, because such conditions facilitate the formation of thaumasite, detriment to the structural integrity of calcium silicate hydrates (C─S─H). In this work, the effect of the cation associated with sulfates, concentration of sulfate solution, and limestone content in cement, were thermodynamically simulated. MgSO4 solution is of higher risk, degrading extensively the structural integrity of C─S─H. Although this phase is partially preserved under the effect of Na2SO4 and K2SO4 solutions, extensive expansion and thaumasite formation occur. The sulfate content of the corrosive solution and the limestone content in cement are the factors mostly intensifying the attack caused by MgSO4 and Na2SO4/K2SO4 solutions, respectively.