Influence of compressive fatigue on the sulfate resistance of slag contained concrete under steam curing

This paper investigated the influence of compressive fatigue on the sulfate resistance of slag (0, 20, 50, and 70%) contained concrete under steam curing. After 10,000 cycles loading of 0.5, 0.6, and 0.7 stress level, the concrete was exposed to 5% Na2SO4 for 540 days. The compressive strength, relative dynamic modulus of elasticity (RDME) and SO42− contents were tested after sulfate immersion. Results showed that the standard‐cured fatigued concrete had less strength reduction than the steam‐cured fatigued concrete during sulfate attack. The steam‐cured fatigued concrete containing 20% slag suffered the largest strength reduction, followed by the concrete containing 50, 70, and 0% slag. Compressive fatigue at high stress level (0.7) accelerated the sulfate deterioration of PC standard‐cured concrete, while the effect of low stress level (0.5) was minor. The RDME was not a sensitive indicator to access the sulfate resistance of concrete at the beginning of immersion. Compressive fatigue distinctly promoted the sulfate diffusion; the effective SO42− diffusion coefficient was increased when damage occurred in slag concrete. Besides, based on the fatigue damage, an experimental model of the sulfate deterioration of fatigued concrete was proposed.