外部氯盐环境对混凝土氯离子结合能力的影响

EFFECT OF EXTERNAL CHLORIDE SALT ENVIRONMENT ON CHLORIDE BINDING CAPABILITY OF CONCRETE

用自然扩散法测定混凝土中的总氯离子和自由氯离子浓度,计算不同种类混凝土对Cl-的结合能力,研究环境介质的种类及其氯离子浓度对混凝土氯离子结合能力的影响。结果表明,环境介质的成分越复杂、浓度越高、其他离子越多,普通混凝土对氯离子的结合能力越弱,掺矿物掺合料的混凝土与此规律基本相同。其中,以3.5%NaCl溶液为基准,普通混凝土、粉煤灰混凝土、硅灰混凝土、矿渣混凝土在(3.5%NaCl+5%MgSO4)溶液中的氯离子结合能力分别降低38%、36.7%、36%、51.7%,在青海盐湖卤水中则降低更多,分别达到58%、64.7%、74.9%、62.1%。因此,在成分复杂、浓度较高的氯盐环境中,应该考虑混凝土对氯离子结合能力的弱化作用。

The total chloride ion and free chloride ion contents of concrete were determined by natural diffusion method.Cl-binding capability was calculated for different kinds of concrete.The influences of the types of environmental media and chloride ion concentration on Cl-binding capacity were discussed.The results show that Cl-binding capacity of common concrete is weakened when composition of environmental medium becomes more complicated,concentration becomes higher and the number of ions is increased.The rule of mineral admixture concrete is basically the same.Cl-binding capacity of common concrete,fly ash concrete,silica fume concrete and slag concrete in（3.5% NaCl ＋ 5% MgSO4） solution are reduced by 38%,36.7%,36% and 51.7% separately,compared to the situation in 3.5% NaCl solution,and those in Qinghai salt lake bittern are reduced respectively by 58%,64.7%,74.9% and 62.1%,from which it can be concluded that the weakening effect of concrete on Cl-should be taken into account in chloride salt environment under the situation of comparatively high concentration and complicated component.