Effect of Compressive Fatigue on Sulfate Ion Diffusion in Standard-Cured and Steam-Cured Concrete Containing Slag

This work assessed the effect of compressive fatigue on sulfate ion diffusion in standard-cured and steam-cured concrete containing slag. After compressive fatigue, the slag concretes were immersed in 5% sodium sulfate solution for 18 months. The sulfate ion content in concrete was measured and the sulfate ion effective diffusion coefficient was calculated. The results showed that compressive fatigue accelerated sulfate ion diffusion in concrete, and the acceleration was more prominent in steam-cured concrete than standard-cured concrete. During sulfate attack, the sulfate ion content in the same layer of standard-cured fatigued concrete grew with an increase in stress level. Massive ettringite with large size was generated in steam-cured fatigued concrete during sulfate attack. In addition, a sulfate ion diffusion model of fatigued concrete was established. Based on this model, the measured values agreed well with the simulated distribution curve of sulfate ions in fatigued concrete.