电化学参数对混凝土除氯效率的影响

为确定氯盐污染混凝土结构的最佳电化学除氯参数，对掺3%水泥质量NaCl的混凝土圆柱体试件进行电化学除氯实验，研究了3种不同电流密度（1、2、3A/m²）和3种不同电解液（自来水、饱和Ca（OH）₂溶液、Na₃BO₃为0.1mol/L）作用下的氯离子排出量随时间的变化规律.结果表明：电流密度越大，通电开始6d内混凝土的除氯速率越快；28d的总除氯量越多，钢筋附近混凝土微观结构劣化和碱性物质富集越多.因此，确定2A/m²为最佳电流密度.相同电流密度通电28d后，自来水中的除氯量大约只有其他2种电解液的50%，因此，应采用碱度较高的饱和Ca（OH）₂溶液或物质的量浓度Na₃BO₃为0.1mol/L的电化学除氯电解液.

Influence of electrochemical parameters on chloride extraction efficiency

In order to determine the optimal parameters of electrochemical chloride extraction （ECE） treatment on the concrete structure contaminated by chloride, ECE treatment was applied to the cylindrical concrete specimens containing NaCl of 3% cement mass. The variation of chloride extraction content with time was studied at three different current densities of 1, 2 and 3A/m² as well as in three different electrolyte solutions including tap water, saturated Ca（OH）₂ solution and 0.1mol/L Na₃BO₃ solution. The results show that with increasing the current density, the chloride extraction speed within first 6 days increases, and the total chloride content extracted from the concrete becomes much more after ECE treating for 28 days. However, the deterioration of microstructure and accumulation of alkaline substance in the concrete near reinforcing steel bars is attributed to a higher current density. Therefore, it is suggested that the optimal current density should be 2A/m² for the ECE treatment on the concrete. After ECE treating for 28 days with the same current density, the total chloride extraction content in tap water is about 50% of that in other two electrolyte solutions. It is recommended that the 0.1mol/L Na₃BO₃ solution or saturated Ca（OH）₂ solution with a high alkalinity should be used as the electrolyte solution for the ECE treatment. 