摘要
针对经受干湿循环作用下氯离子侵蚀致使混凝土耐久性劣化的问题,采用在不同环境相对湿度条件下浸泡和喷淋的方式模拟干湿循环作用,通过测定侵入混凝土试件内部不同深度的自由氯离子含量和氯离子总含量,借鉴生长曲线函数中的Hill模型,探讨了干湿循环作用下,锂渣的掺量、环境相对湿度以及侵蚀氯盐质量分数等因素对混凝土氯离子扩散性能的影响。研究结果表明:干湿循环作用下,随着环境相对湿度的降低和侵蚀氯化钠溶液质量分数的增大,侵入混凝土内部的氯离子总含量达到阀值所需要的时间逐渐延长。锂渣替代水泥20%时,Hill系数n值最小,侵入混凝土内部氯离子总含量达到阀值所需要的时间最长。锂渣混凝土内部取样深度1~5 mm时,自由氯离子含量排序为(RH=40%条件)>(RH=80%条件)>(RH=60%条件)>(RH=100%条件)。干湿循环作用下,混凝土内部的氯离子总含量并不随着相对湿度的递减而单调增加。
The deterioration of concrete durability was caused by chloride ion erosion under the action of dry and wet circulation. The dry and wet circulation was simulated by immersion and spray under different relative humidity conditions. By measuring the free chloride ion content and the total chloride ion content in different depths of the intrusive concrete specimens,based on the Hill model in the growth curve function,the effects of lithium slag content,environmental relative humidity and erosive chloride mass fraction on the chloride ion diffusion properties of concrete under dry and wet cycles were investigated. The result indicates that under the dry-wet cycle,the time required for the total content of chloride ions in the interior of the concrete to reach the threshold is gradually prolonged as the relative humidity of the environment decreases and the mass fraction of the etched sodium chloride solution increases. When the lithium slag replaces the cement by 20% and the Hill coefficient n is the smallest,the total time required for the total chloride ion content in the intrusive concrete to reach the threshold is the longest. When the internal sampling depth of lithium slag concrete is 1 mm to 5 mm,the order of free chloride ion content is( RH = 40% condition) >( RH = 80% condition) >( RH = 60%condition) >( RH = 100% condition). The total chloride ion content inside the concrete under the dry and wet cycle does not increase monotonously with the decreasing of relative humidity.
引文
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