Investigations of Sulfuric Acid Corrosion of Concrete. I: Modeling and Chemical Observations

Degradation of a mortar specimen exposed to an acid sulfate solution was studied. The pH of the solution was maintained in the range of 4-5 for 8 days and 2-3 for 73 days. Data from the experiment were used to investigate the efficacy of a diffusion-reaction based model with a moving boundary for the corrosion process. Acid neutralization rates in the solution were used to calculate the corrosion rate constant for the mortar sample and to determine the effective diffusion rate of sulfuric acid in the corrosion layer. Visual observation of the cross section of the sample at the end of the experiment indicated that 0.82 mm was corroded. The data established the validity of the moving boundary paradigm for sulfide corrosion of concrete when the effective diffusion rate was a decreasing function of the age of the corrosion product being formed.