Abstract
In this paper, we discuss a deterioration phenomenon of concrete due to sulfuric acid and sodium sulfate attack in environments which contain sulfuric acid and sulfate simultaneously. Specimens were immersed to some kinds of solutions which have different pH and SO42- concentration, and chemical and physical changes of specimens were analyzed. As the result of analyses, we identified that the feature of deterioration can be classified into 3 categories by using the pH value and the SO42- concentration of the solutions. If the SO42- concentration is low, the deterioration of concrete was mild even in the pure sulfuric acid solution of pH2-3. In the case of pH of more than 3 and high SO42-, cracks were generated by ettringite formations. In the case of pH of less than 2-3 and high SO42-, vulnerable gypsum layer was formed, and partial loss became greater. When deterioration velocity and weight loss velocity of the specimens were compared, it became clear that the deterioration became intense synergistically by the simultaneous action of sulfuric acid and SO42-.
