An integrated macro-microscopic model for concrete deterioration under external sulfate attack

• Published in: Engineering fracture mechanics 2020-12, Vol.240, p.107345, Article 107345
• Main Authors: Yin, Guang-Ji, Zuo, Xiao-Bao, Li, Xiang-Nan, Zou, Yu-Xiao
• Format: Article
• Language: English
• Subjects: Concrete deterioration; Crystallization; Crystallization pressure; Damage assessment; Ettringite; External sulfate attack (ESA); Gypsum; Integrated macro-microscopic model; Volume increase
• ISSN: 0013-7944; 1873-7315
• DOI: 10.1016/j.engfracmech.2020.107345

•ESA-induced deterioration of concrete is divided into dormant and detrimental periods.•An integrated macro-microscopic model for concrete deterioration is developed.•Diffusion, reaction of sulfate and its-induced expansion of concrete can be analyzed.•Deterioration process of concrete pipe exposed to Na2SO4 solution is investigated. Concrete deterioration caused by external sulfate attack (ESA) is a macro-microscopically interactive expansion process, including two stages, namely a dormant period and detrimental duration. Based on ESA-induced deterioration mechanism, an integrated macro-microscopic model has been developed to describe the deterioration of concrete. In this model, a critical characteristic related to crystallization pressure is proposed to recognize two stages of ESA, and a criterion of ESA-induced boundary movement in concrete specimen is established by its total damage associated with micro and macroscopic damages. A diffusion-reaction model is constructed to characterize macroscopic sulfate diffusion and microscopic ettringite/gypsum formation in concrete, which are respectively used to determine the crystallization pressure and volume increase. The macro and microscopic mechanical models, combining with the plastic-damage model, are built to analyze the expansion-induced deterioration of concrete. The integrated model is validated by the experimental results of expansion deformation and damage distribution.