沿海混凝土结构的环境盐雾分区研究

处于近海盐雾区的混凝土结构,其表面的氯离子浓度是随着时间的增长而逐步累积的,同时又是随着距海岸距离及离海面高度的增大而降低的.根据这一特点,建立在近海陆上和海上盐雾区环境下以时间、距离和高度为变量的混凝土结构表面的氯离子浓度模型,在该边界条件下根据Fick第二扩散定律建立一维扩散模型方程.根据计算出的混凝土保护层厚度,进行近海盐雾区的分区,即轻度盐雾区和重度盐雾区.通过模型计算结果,分析了水胶比对不同设计使用寿命时混凝土保护层厚度的影响.

Study on environment zoning of concrete structures in coast areas

In salt-spray area,the chloride concentration on the surface of concrete structures can increase continuously along with time,and decrease with the increase of the distance to the coastline and the height from the sea surface.According to this property,a mathematical model of chloride concentration on the surface of concrete can be set up by using parameters of time,distance and height.Based on Fick's second law of diffusion,a new one-dimensional diffusion equation can be deduced on the above-mentioned boundary condition.According to the concrete cover thickness by calculating,a salt spray zone at the seaside is obtained,i.e.,slight zone and severe zone.Though the calculated value of diffusion model,influences of W/B ratio on concrete cover thickness with different design service life are analyzed.