Damage evolution is detected via the degradation of modulus of concrete immersed in sulfate solution. The mechanism of the damage is investigated by using SEM method, and it is proved that the internal expansion stress induced by delayed ettringite leads to the nucleation of micro-cracks. The criterion of damage nucleation is proposed in terms of the tension strength of concrete. The differential equation with respect to the internal expansion stress is derived by virtue of chemical reaction rate on delayed ettringite formation, and a new chemo-mechanical model of corrosion damage in concrete under sulfate attack is then proposed. (C) 2016 Elsevier Ltd. All rights reserved.

The financial support by National Natural Science Foundation of China (NSFC # 51079069), the Key Research Program of Society Development of Ningbo (2013C51007), the National Basic Research Program of China (973 Program, 2009CB623203), and K.C. Wong Magna Fund in Ningbo University are gratefully acknowledged.