低中放射性废物处置用高整体容器密封材料的制备与性能研究

Preparation and Performance of Sealing Materials for High Integrity Containers for Low and Intermediate Radioactive Waste Disposal

为开发具备大流动性、高强度和高耐久性能的高整体容器黏接填充密封材料,并使其能满足在低中放射性废物处置过程中多种严酷环境下服役300年的要求,本文以硅酸盐水泥、硅灰为胶凝材料,磨细石英砂为惰性填充材料,通过颗粒最紧密堆积原理获取初步配方,并以硅微粉替代部分水泥后,研究硅微粉对密封材料流变性能、孔隙结构、力学性能、耐久性能以及氮气渗透系数的影响。结果表明:硅微粉提高了密封材料的流动度及流变性能,降低了28和56 d的孔隙率,提高了劈裂抗拉强度、抗收缩性能、抗化学侵蚀性能、抗渗性能以及抗冻性能,但对其抗压强度及静弹性模量作用不明显。加入10%(质量分数)硅微粉的密封材料各项性能均优于国家标准要求,可以满足在严酷环境下安全服役300年要求。

In order to develop the bonding and sealing materials for high integrity container with large flowability,high strength and high durability,so as to meet the requirements of 300 years service in a variety of harsh environments during the process of low and intermediate radioactive waste disposal,ordinary Portland cement and silica fume were used as cementitious materials,and fine quartz was used as intert filer.Based on the most compact stacking theory,preliminary formulation was obtained.Micro silica powder was introduced to partially replace cement,and rheological properties,pore structure,mechanical properties and durability of sealing materials were investigated.The results show that micro silica powder improves the fluidity and rheological properties,reduces the porosity at 28 and 56 d,and improves the splitting tensile strength,shrinkage resistance,chemical attack resistance,seepage resistance and freeze-thaw resistance of sealing materials,but the effect of micro silica powder on compressive strength and static elastic modulus is not obvious.After adding 10%(mass fraction)micro silica powder into cement,the properties of sealing materials are higher than those required by the Chinese standards and satisfies the demand of 300 years of service in harsh environment.