水和氯离子在砂浆中的迁移规律

Migration of Water and Chloride Ions into Mortar

研究了水灰比、氯盐浓度对砂浆中水和氯离子侵入规律的影响和砂浆的微观形貌,通过磨粉滴定的方法测定了氯离子含量,分析了毛细吸盐条件下水和氯离子传输之间的相关性规律。结果表明:氯离子的传输以水为载体,但明显滞后于水的传输,两者非同步;水灰比为0.6砂浆试件中的水侵入深度大约为氯离子侵入深度的2倍,水灰比为0.4试件的水侵入深度是氯离子的1.5倍左右;毛细吸盐7 d后,水灰比为0.6砂浆内部容易形成氯化钠结晶,延缓水迁移;在毛细吸附初始阶段,水渗透深度与氯离子渗透深度之间近似呈现线性相关,随着时间的增长,水分迁移变缓,氯离子在浓度梯度作用下继续向深处扩散;氯盐浓度超过6%后,氯离子侵入量不再随盐浓度的增大而增大。

The influences of water-cement ratio and concentration of NaC1 solution on the water and chloride ions penetration into cement mortar were investigated. The microstructure of mortar was determined by scanning electron microscopy, and the chloride content was measured by a titration method. The relationship between water penetration and chloride penetration into mortar was analyzed. The results indicate that chloride ions transport in water at the beginning, but they gradually slow down and separate from water movement. Chloride ions are much behind of the waterfront. The penetration depth of water into mortar with a water-cement ratio of 0.6 is approximately two times as the penetration depth of chloride. The water penetration depth in mortar with a water-cement ratio of 0.4 is approximately 1.5 times as the penetration depth of chloride. After 7 d capillary suction, the crystallization of sodium chloride in the cement mortar with a water-cement ratio of 0.6 can form in the pores, which affects the transport of water. At the initial stage, the relationship between the penetration depths of water and chloride ions exhibits linear. The water movement slows down, while chloride penetrates further into deep driven by the concentration gradients of chloride ions. When the concentration of NaC1 solution is 〉 6%, the amount of chloride ions may not increase with the increase of the concentration of NaCI solution.