Accelerated test for measuring sulfate resistance of calcium sulfoaluminate, calcium aluminate, and portland cements

Sulfate ions present in soil, ground water, seawater, decaying organic matt er, and industrial effluents are known to have an adverse effect on long-te rm durability of concrete. However, ASTM test methods for predicting sulfat e resistance have been criticized for failing to adequately predict field p erformance. In this investigation, cement pastes were tested by an accelera ted test method where pH and sulfate concentration remained constant, condi tions that are more representative of field conditions. A total of eight ce ments were tested: three portland cements (Type I/II, Type III, and Type V) ; one calcium aluminate cement (CA1); two calcium sulfoaluminate cements (C SA1 and CSA2); and two blends containing calcium aluminate, anhydrite, and portland cement (CAPC1 and CAPC2). After 63 days of exposure to a 4% Na2SO4 solution where the pH was maintained at 7.2, sulfate resistance of the cem ents can be described by: CA1 = CSA2 = Type I/II > Type V > Type III > CAPC 2 > CAPC1 > CSA1.