Na_2CO_3对回填材料膨润土的改型效果分析

以新疆柯尔碱膨润土为原料,加入不同比例的Na2CO3改型剂,研究改型剂添加对膨润土胶质价、膨胀容和pH值的影响。另外,考虑到压实膨润土的非饱和渗透特性对于评价缓冲回填材料性能具有重要意义,故采用压力膜仪测量压实Na2CO3改型膨润土和原土的土水特征曲线,分析研究二者基质吸力随体积含水率变化的相关关系。实验结果显示,添加Na2CO3改型剂可以增大膨润土的胶质价、膨胀容和pH值,成功地将膨润土中的钙蒙脱石转化为钠蒙脱石,其对柯尔碱膨润土pH值的作用效果满足地质处置库对缓冲回填材料的要求;改型后膨润土的持水能力明显大于原土。

The Analysis of Na2CO3’s Modified Effection in Bentonite as a Buffer Backfill Material

Used Xinjiang Cole alkali bentonite as the raw material and added different proportions of Na2CO3,to study the effection of adding modification to colloid valency,expansion volume and pH of bentonite.In addition,considered that non-saturated hydraulic properties of compacted bentonite is significant to the evaluation of backfill and buffer material properties.So the author used pressure plate extractors to measure soil-water characteristic curve of the original bentonite and Na2CO3 modified bentonite,to analyze the relationship between matrix suction and volumetric water content.The experimental results showed that adding Na2CO3 modification could increase bentonite’s valency,expansion volume,pH and transform calcium montmorillonite to sodium montmorillonite successfully.The influence of the pH of Cole alkali bentonite meets the requirements of geological repository to backfill and buffer material.Water-holding capacity of modified bentonite is significantly lager than the original bentonite.