混凝土盐结晶破坏的研究

Deterioration of Concrete due to Action of Salt Crystallization

以混凝土剥落量、膨胀率和强度损失率为评价指标,研究了干湿循环条件下Na2SO4和NaCl盐结晶对混凝土的破坏,并与在Na2SO4和NaCl盐溶液中浸泡的混凝土的化学侵蚀破坏结果进行对比.研究表明,混凝土在干湿循环条件下发生的盐结晶破坏明显比化学侵蚀破坏严重;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,且超过一定干湿循环次数后,混凝土经干燥后非但不收缩,反而继续膨胀;盐晶体刚开始主要起密实与增强作用,只有当盐晶体量超过一定值后,才会引起混凝土发生膨胀和破坏;引气可以显著降低和延缓混凝土的盐结晶破坏.

Effects of salt crystallization of Na2SO4 and NaCl on concrete exposed to drying-wetting cycles were investigated by using index including concrete scaling amount, concrete expansion rate and strength loss rate, and chemical attack of concrete soaked in Na2SO4 and NaCl solutions was also measured. The test results show that the deterioration of concrete caused by salt crystallization is much more severe than that caused by chemical attack. The scaling and expansion of concrete due to the action of salt crystallization significantly increase with the increase of salt con- centration and number of drying-wetting cycle, and the concrete after drying does not shrink but expands when the number of drying-wetting cycle is over a certain value. The salt crystals have some compacting and strengthening effects on the concrete at first, and the expansion and deteri- oration of the concrete occur only when the amount of salt crystals is over a certain value. The salt-crystallized deterioration of concrete is significantly mitigated by air-entraining.