潮差环境下混凝土中氯离子扩散时变性试验

Experimental Study on Time-Variation of Chloride Diffusivity in Concrete under Natural Tidal Environment

以自然海洋潮差区环境条件下暴露时间分别为60,120,240,360,480,600d的混凝土现场试验结果为基础,计算了5种水灰比混凝土的氯离子扩散系数;以60,120,240,360,480d的氯离子扩散系数测量结果,推导了潮差环境下混凝土中氯离子扩散系数的时变模型,并以该时变模型计算了暴露600d后混凝土中氯离子扩散系数及自由氯离子含量,验证了该时变模型的适用性.结果表明:水灰比越大,混凝土中氯离子扩散系数在前期衰减的经验系数m越小,即对降低混凝土氯离子长期扩散性能的效果越差,因此减小水灰比能有效降低混凝土的长期氯离子扩散性能;暴露600d后混凝土中氯离子扩散系数降低幅度已经很小,基本趋于稳定;得到的混凝土氯离子扩散系数时变模型能较好地反映潮差环境下混凝土中氯离子侵蚀过程.

Based on the field experiment of concretes exposed to marine tidal environment for 60,120,240,360,480,600 d,the chloride diffusion coefficients of concretes with 5 water-cement ratios were determined.According to the chloride diffusion coefficients of concretes exposed for 60,120,240,360,480 d,the time-variation model of chloride diffusion coefficient in concrete was deduced under natural tidal environment.Based on the results above,chloride diffusion coefficient and free chloride content of concrete exposed for 600 dwere calculated by the time-variation model,and the adaptability of the time-variation model was verified.Results indicate that the higher water-cement ratio of concrete is,the lower attenuation coefficient of chloride diffusion coefficient is,the poorer reduction effect of long-term chloride diffusivity in concrete is.Thus reduction of water-cement ratio of concrete is effective to reduce long-term chloride diffusivity in concrete.The decrease range of chloride diffusion coefficient in concrete exposed for 600 dis very narrow,and the chloride diffusion coefficient of concrete is stable basically after 600 d.The time-variation model of chloride diffusion coefficient in concrete can better reflect the chloride erosion process in concrete under natural tidal environment.