Influence of cement composition on the corrosion of reinforcement and sulfate resistance of concrete

Performance data based on accelerated corrosion-monitoring and exposure site tests indicate that cement type, reflecting particularly the C₃A content, significantly affected concrete durability with respect to corrosion of reinforcing steel. On average, Type I cement (C₃A = 9.5 percent) performed 1.7 times better than Type V cement (C₃A = 2.8 percent) in terms of time of initiation of corrosion. Accelerated sulfate-resistance tests show that a 20 percent microsilica blended with Type I 14 percent C₃A cement performed 1.4 times better against sulfate attack than a Type V portland cement with 1.88 percent C₃A. Also, sulfate deterioration data indicate that, in addition to the C₃A content, the C₃S/C₂S ratio of the cement has a significant effect on the sulfate resistance of the cement. Additional study results are discussed.