Deterioration rate of hardened cement caused by high concentrated mixed acid attack

• Deterioration of hardened cement caused by pure strong acid attack was clarified.
• Deterioration of hardened cement caused by mixed strong acid attack was clarified.
• Dissolution of Ca(OH)2 model of deteriorated by mixed acid is constructed.

The purposes of this study are to clarify the deterioration mechanism of hardened cement caused by high concentrated acid attack. As the result, In the case of high concentrated pure acid, deterioration rate varies greatly according to the kind of product of the attack of acid. This behavior can be explained by solubility of product. Next, in the case of which mixed acids containing H2SO4, HCl or HNO3 is attacking on hardened cement, the deterioration rate begins to increase when H2SO4 molar fraction decreases from between about 0.7 and 0.4–0.0. This behavior can be explained by chemical kinetics.