Dry–wet cycle conditions have significant effects on the corrosion of concrete under sulfate attack. However, previous studies have only applied them as a method for accelerating sulfate attack and not systematically studied them as an object. In order to explore the impact of sulfate attack with different dry–wet cycle periods on concrete, in this study, four dry–wet cycle periods (3, 7, 14, and 21 days) were selected. The flexure strength, relative dynamic modulus, and mass were tested, and the microstructures of the eroded specimens were also analyzed. The intensity and depth of sulfate erosion were influenced by the wet–dry cycle period. The results show that the deterioration of concrete first increased and then decreased with an extension of the dry–wet cycle period. Microstructural analysis indicated that, with an increase in the dry–wet cycle period, the corrosion depth of sulfate attack increased. Moreover, the erosion products such as ettringite and gypsum were greatly increased, in agreement with the macroscopic variations. However, excessively prolonging the dry–wet periods does not significantly further the deterioration of concrete’s performance. Therefore, considering the strength and depth of corrosion caused by sulfate attack, it would be appropriate to employ dry–wet cycle periods of 7–14 days under natural dry conditions in studies on concrete.

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干湿循环周期对硫酸盐侵蚀下混凝土性能的影响

干湿循环条件对硫酸盐侵蚀下的混凝土腐蚀具有重要影响。但是，以前的研究仅将它们用作加速硫酸盐侵蚀的方法，而没有系统地研究它们作为对象。为了探讨不同干湿循环周期对硫酸盐的侵蚀对混凝土的影响，在本研究中，选择了四个干湿循环周期（3、7、14和21天）。测试了弯曲强度，相对动态模量和质量，并分析了腐蚀试样的微观结构。硫酸盐侵蚀的强度和深度受干湿循环周期的影响。结果表明，随着干湿循环周期的延长，混凝土的劣化先增加后减少。微观结构分析表明，随着干湿循环时间的增加，硫酸盐侵蚀的腐蚀深度增加。而且，与宏观变化相一致，诸如钙矾石和石膏的侵蚀产物大大增加。但是，过度延长干湿时间不会明显加剧混凝土性能的下降。因此，考虑到硫酸盐侵蚀引起的腐蚀强度和深度，在混凝土研究中，在自然干燥条件下采用7-14天的干湿循环周期是适当的。过度延长干湿时间不会明显加剧混凝土性能的下降。因此，考虑到硫酸盐侵蚀引起的腐蚀强度和深度，在混凝土研究中，在自然干燥条件下采用7-14天的干湿循环周期是适当的。过度延长干湿时间不会明显加剧混凝土性能的下降。因此，考虑到硫酸盐侵蚀引起的腐蚀强度和深度，在混凝土研究中，在自然干燥条件下采用7-14天的干湿循环周期是适当的。