Accelerated sulfate attack on mortars using electrical pulse

• The effect of electrical pulse on sulfate attack was investigated.
• Electrical pulse greatly accelerated the migration of sulfate ions into mortars.
• Electrical pulse accelerated the sulfate attack on mortars.
• Electrical pulse could be a novel method for rapidly evaluating the sulfate resistance of cement-based materials.

In this study, the sulfate attack on mortars was accelerated using electrical pulse as an external electrical field. Meanwhile, the specimens with the same mix proportions were immersed in sulfate solution as comparison. The sulfate concentration and mechanical properties, including flexural and compressive strengths, were measured to evaluate the effects of sulfate attack. In addition, the transformation of microstructural nature and phase of the specimens were evaluated by scanning electron microscope and X-ray diffraction. The results showed that electrical pulse greatly accelerated the penetration of sulfate ions into the mortars and resulted in more ettringite and gypsum formed, leading to a greater depth of sulfate reaction. In electrical pulse test, the sulfate content in MgSO4 solution was greater than that in Na2SO4 solution, which was the opposite case in immersion test. Moreover, the electrical pulse resulted in significant mechanical strength losses in a much shorter period as compared with those in immersion test. These findings indicated that the electrical pulse accelerated sulfate attack could be a new acceleration test for evaluating the sulfate resistance of cement-based materials.