摘要
pH值小于11的低pH胶凝材料是高放废物处置库建造所需的关键材料。为支撑我国北山高放废物地质处置地下实验室和未来处置库的建设,本文采用破碎溶出法,研究普通硅酸盐水泥掺入不同矿物掺合料后硬化体pH值的变化规律,得到了低pH胶凝材料的配比。通过渗透、浸泡和极限溶出试验评价了低pH胶凝材料的可靠性,借助X射线衍射和扫描电镜,结合室内试验,测定分析了其水化产物、抗压强度和流变参数,并评估了其对北山地下水环境的影响。结果表明:胶凝材料中CaO/SiO2(质量比)与硬化体pH值呈线性关系,低pH胶凝材料的基础配比为在普通硅酸盐水泥中掺入40%的硅灰,硬化体渗透水和浸泡水的pH值分别在约28 d和90 d降低至11以下,在万年尺度分解为松散颗粒时的最大pH值约为11.2,满足处置库要求。与普通硅酸盐水泥相比,低pH胶凝材料150 d水化产物中不含氢氧化钙,胶砂体28 d抗压强度更高,但相同水胶比时注浆浆液的黏稠度更大;按照水固比1∶1浸泡硬化体,浸泡水的主要离子浓度变化幅度不大,对北山地下水环境的影响更小。
Low-pH(pH<11)cementitious material is the key to the construction of high-level radioactive waste(HLW)disposal repository.In China,the first underground research laboratory(URL)for gelogical disposal of HLW is located in Xinchang site of Beishan area,Gansu province,and the construction work was started in June of 2021.In order to support the construction of Beishan URL and future disposal repositories of the HLW,the crushing-leaching method was adopted to study the change rule of the pH values of the ordinary Portland cement(OPC)with different mineral admixtures,such as silica fume(SF),fly ash(FA),ground granulated blast furnace slag(GGBFS),and the low-pH cementitious material was prepared in this paper.To satisfy the goals of various types of water in HLW repository should be lower than 11,reliability of low-pH cementitious material was validated by penetration,soaking,and extreme leaching methods.For understanding the engineering properties of low-pH cementitious material,its hydration products,compressive strength,rheological parameters were analyzed by using XRD,SEM and combined with other indoor laboratory tests.Finally,hardened sample of low-pH cementitious material was soaked in Beishan groundwater,and its influence on groundwater environment was assessed by studying the change process of main ion concentration in soaked water.The results show that the pH values of the hardened samples are linearly correlated with the weight ratios of CaO/SiO 2 containing in the cementitious material,and the low pH base ratio is the mixture of the OPC with 40%SF,and if compunding admixtures of SF and FA were added in OPC to reduce the cost of low-pH cementitious material,the weight ratio of CaO/SiO 2 should be lower than 0.53.pH values of penetration and soaking water in the hardened mixtures of OPC with 40%SF are below 11 after about 28 days and 90 days,respectively,and the maximum values is about 11.2 if the hardened samples decompose to loose particles on a 10000-year scale,which are satisfied with the requirements of r
作者
路威
赵卫全
陈亮
张金接
周建华
王驹
LU Wei;ZHAO Weiquan;CHEN Liang;ZHANG Jinjie;ZHOU Jianhua;WANG Ju(China Institute of Water Resources and Hydropower Research,Beijing 100038,China;Beijing Research Institute of Uranium Geology,Beijing 100029,China;CAEA Innovation Center for Geological Disposal of High-Level Radioactive Waste,Beijing 100029,China)
出处
《原子能科学技术》
EI
CAS
CSCD
北大核心
2023年第5期909-919,共11页
Atomic Energy Science and Technology
基金
核设施退役治理专项资助科研项目(科工二司[2020]194号)。
关键词
高放废物地质处置
低pH胶凝材料
水化产物
抗压强度
流变参数
地下水环境
high-level radioactive waste geological disposal
low-pH cementitious material
hydration product
compressive strength
rheological parameter
groundwater environment
