Degradation mechanism of blended cement pastes in sulfate-bearing environments under applied electric fields: Sulfate attack vs. decalcification

Applied electric fields , the reason behind stray currents, accelerate ingress of sulfate into cementitious materials . To identify mitigation approaches, this study investigates effects slag and fly ash on sodium attacks cement pastes under a constant current. The mineralogical alterations induced by were analyzed using X-ray diffractometry, thermogravimetric analysis scanning electron microscopy, thermodynamic modeling dissolution aluminates in monosulfate-rich area (>∼20 mm from cathode surface) to form next ettringite-rich sample surface (<∼20 mm). This effect reduced availability SO 4 2− pore solution thereby hindering penetration sulfate. Meanwhile, consumption portlandite pozzolanic reaction lowered decalcification resistance materials. produced wide that endured decomposition carbonate-AFm. Overall, blending 30% did not improve material either or decalcification; 50% can effectively mitigate ingress, though may become governing mechanism degradation process