Effect of multiple ions on the degradation in concrete subjected to sulfate attack

作者：Wu, Jiang; Wei, Jiangxiong^*; Huang, Haoliang; Hu, Jie; Yu, Qijun

来源：CONSTRUCTION AND BUILDING MATERIALS, 2020, 259: 119846.

DOI：10.1016/j.conbuildmat.2020.119846

• Sulfate attack
• Chloride
• Carbonate
• Degradation of concrete
• Multiple ions

Influence of multiple ions on sulfate attack on concrete was studied by measuring the mass change and elasticity modulus (E-rd) change and observing cracks at different scale. X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermo gravimetric analysis (TGA) were used to study the evolution of microstructure of concrete during the process of sulfate attack influenced by multiple ions. Diffusion coefficient and thermodynamic modelling were used to study the interactions between the ions and the concrete. It can be summarized that the cation compound in sulfates has a significant impact on the behaviors and mechanism of the degradation of concrete. The presence of chlorides has a mitigating effect on magnesium sulfate attack and delay the deterioration in the early stage, but promoted the migration of sulfate inside the concrete in the later stage. For coupled attacks by multiple ions, i.e. Cl, SO42+ and CO32, the ingress of sulfate and chloride into the concrete was influenced by the interactions between those ions. The calcium carbonate with low solubility precipitates in the pore network and decreases the porosity of concrete. As a result, no obvious deterioration and just a few micro-cracks were found in this study.