A study on the reaction mechanism of hardened cement chemically damaged by mixed acids

It is well known that the concrete under acidic environment is deteriorated due to a chemical attack. For example, acid rain cause concrete unexpectedly short service life due to the damages for concrete cover. For these background, the purpose of this study are (1) to clarify the relation between sulfuric acid mol fraction of mixed acids and mass decrease rate of hardened cement deteriorated by mixed acids and (2) these relations are arranged with physical chemistry theories. From the experimental results, in the case of sulfuric acid mol fraction of mixed acids are larger than about 0.40, mass decrease rate are at the same as deteriorated by sulfuric acid. On the other hand, in the case of sulfuric acid mol fraction of this are smaller than about 0.40, mass decrease rate increase liner and finally mass decrease rate are at the same as deteriorated by nitric acid or hydrochloric acid.