海水侵蚀环境下粉煤灰对清水混凝土耐久性的影

    摘要：采用抗压强度、电通量及RCM法、XRD和SEM，研究了粉煤灰对清水混凝土在海水侵蚀环境下耐久性的影响规律。结果表明：粉煤灰的掺入对清水混凝土后期强度没有明显降低作用，甚至略有提高，电通量及氯离子扩散系数均降低；XRD结果显示，海水的侵蚀会导致水泥浆体中Ca（OH）2含量降低，AFm向AFt转变，同时生成大量Friedel盐，而掺入粉煤灰后可生成更多的Friedel盐，固化海水周围的Cl-，减少Cl-对钢筋混凝土的锈蚀破坏作用，从而提高清水混凝土抗侵蚀性能；SEM结果显示，粉煤灰的掺加减少了钙钒石的生成，同时也使胶凝材料结构变的更加致密，降低了孔隙率，减少了海水的侵蚀破坏。

    关键词：粉煤灰；氯离子扩散系数；海水侵蚀；清水混凝土；耐久性

    中图分类号：TU528        文献标识码：A        文章编号：1001-702X（2018）05-0014-04

 

The effect of fly ash on the durability of fair-faced concrete under seawater erosion environment

TAO Yeping1，GU Kunpeng2，ZHONG Sai2

（1.Quality and Safety Surveillance of Shanghai Railway Bureau，Shanghai 200071，China；

2.CCCC Shanghai Third Harbour Engineering Academy of Science Co. Ltd，Shanghai 200032，China）

    Abstract：Concrete compressive strength test，test of electric flux and RCM method，XRD and SEM test technology were used to study the influence law of fly ash on durability of fair-faced concrete under seawater erosion. The results show that：the incorporation of fly ash has no significant effect on the long-term strength of the fair-faced concrete，and even slightly improves the strength of the fair-faced concrete. At the same time，the mixing of fly ash reduces the electric flux of concrete and the diffusion coefficient of chloride ion；XRD results showed that the seawater erosion results in the decrease of Ca（OH）2 in cement paste，AFm turning to AFt，and generates large amounts of Friedel salt，and cementitious paste after mixing fly ash can generate more Friedel salt，cure Cl- around the seawater，reduce the corrosion damage of Cl- on reinforced concrete，so as to improve the anti-erosion performance of concrete；SEM results showed that the addition of fly ash has reduced the formation of ettringite，and also makes the structure of cementitious material more compact，lowers porosity，and reduces the damage of seawater erosion.

    Key words：fly ash，chloride diffusion coefficient，seawater erosion，fair-faced concrete，durability