硫酸钠盐结晶对混凝土破坏的影响

研究了Na2SO4盐结晶对干湿循环作用下混凝土剥蚀破坏、膨胀率和强度的影响,以及降温作用下Na2SO4溶液体积膨胀率和结晶压的变化.结果表明:Na2SO4盐结晶产生的混凝土膨胀和剥蚀破坏随着盐浓度和干湿循环次数的增加明显增大,且超过一定循环次数后,经干燥后的混凝土非但不收缩,反而继续膨胀.在降温作用下,Na2SO4溶液盐结晶体积膨胀率和结晶压随着盐浓度增加显著增大,且开始出现膨胀和结晶压的温度也提高,其产生的盐结晶压可超过7MPa,足以引起混凝土破坏.

EFFECTS OF SALT-CRYSTALLIZATION OF SODIUM SULFATE ON DETERIORATION OF CONCRETE

The effects of salt-crystallization of Na2SO4 on the scaling deterioration, expansion and strength of concrete exposed to drying-wetting cycles, and the variation of volume expansion and salt-crystallization pressure of Na2SO4 solution due to the cooling action were investigated. The results show that the scaling and expansion of concrete due to the action of salt-crystallization obviously increase with the increase of the salt-concentration and the number of drying-wetting cycles, and the concrete after drying does not shrink, but expands when the number of drying-wetting cycles is over a certain value. The volume expansion and salt-crystallization pressure of the Na2SO4 solution due to the cooling action increase obviously with the increase of the Na2SO4 concentration, and the temperature that starts to generate the volume expansion and salt-crystallization pressure becomes higher. The salt-crystallization pressure can be over 7 MPa, high enough to cause the deterioration of concrete.