Judžentienė Asta, Zdaniauskienė Agnė, Ignatjev Ilja, Druteikienė Rūta
Department of Organic Chemistry, Center for Physical Sciences and Technology, Saulėtekio Avenue 3, 10257 Vilnius, Lithuania.
Department of Nuclear Research, Center for Physical Sciences and Technology, Savanorių Avenue 231, 02300 Vilnius, Lithuania.
Materials (Basel). 2024 Apr 23;17(9):1940. doi: 10.3390/ma17091940.
Cementitious materials are used to construct an engineered barrier in repositories for radioactive waste. The cement matrix may contain a variety of organic compounds, some of which are polymeric admixtures used as plasticizers. Superplasticizers (SPs) are highly effective organic cement additives for reducing water amount, increasing workability, homogeneity, plasticity and the non-segregation of mortars and grouts, improving mechanical properties and resistance to destructive environments. SPs in cement could have an impact on the long-term safety of the disposals of radioactive waste. These organic agents can leach from the cementitious matrix into groundwater and may affect the migration behaviour of radionuclides. The detailed chemical composition and other characteristics of the cement (CEM I 42.5 R, Sweden) used for the leaching experiments were evaluated. It contained mainly CaO (52.51 ± 1.37, %), and the surface area of the cement particles was 13.2 ± 1.3 m/g. An insignificant increase in pH (from 12.6 ± 0.1 to 12.8 ± 0.1) was observed for the leachates over 10 days. A commercially available cement superplasticizer based on polymelamine sulphonate (PMS) Peramin SMF10 (Peramin AB, Sweden) was chosen for the research. The product's chemical composition was analysed using wavelength-dispersive X-ray fluorescence (WD-XRF) spectroscopy, while other physico-chemical properties of the PMS superplasticizer were assessed by Raman spectroscopy and thermo-gravimetric analysis. In aqueous solutions and powders of PMS, the same most intensive features were observed at 774 cm (ring out-of-plane deformation), 977 cm (C-N-C bending, SO stretching) and 1055 cm (C-N=C bending) in the Raman spectra. At up to 270 °C, the polymer was thermally stable. Raman and UV/Vis spectroscopies were used to assess the rate of the alkaline degradation of PMS superplasticizer in different aqueous solutions. No changes were observed in the hydrolytic solutions with any of the above analytical methods over a period of 3 years. The results obtained revealed a good thermal and chemical stability (in highly alkaline media, pH = 9.9-12.9) of the PMS polymer.
胶凝材料用于在放射性废物储存库中构建工程屏障。水泥基体可能含有多种有机化合物，其中一些是用作增塑剂的聚合物外加剂。高效减水剂（SPs）是非常有效的有机水泥添加剂，可减少用水量，提高砂浆和灌浆的工作性、均匀性、可塑性和抗离析性，改善机械性能以及对破坏性环境的抵抗力。水泥中的高效减水剂可能会对放射性废物处置的长期安全性产生影响。这些有机试剂会从胶凝基体中沥滤到地下水中，并可能影响放射性核素的迁移行为。对用于浸出实验的水泥（瑞典CEM I 42.5 R）的详细化学成分和其他特性进行了评估。其主要成分是CaO（52.51 ± 1.37,%），水泥颗粒的表面积为13.2 ± 1.3 m/g。浸出液在10天内pH值有不显著的升高（从12.6 ± 0.1升高到12.8 ± 0.1）。本研究选用了一种市售的基于聚三聚氰胺磺酸盐（PMS）的水泥高效减水剂Peramin SMF10（瑞典Peramin AB公司）。使用波长色散X射线荧光（WD-XRF）光谱分析了该产品的化学成分，同时通过拉曼光谱和热重分析评估了PMS高效减水剂的其他物理化学性质。在PMS的水溶液和粉末中，拉曼光谱在774 cm（环面外变形）、977 cm（C-N-C弯曲，SO伸缩）和1055 cm（C-N=C弯曲）处观察到相同的最强特征峰。在高达270 °C时，该聚合物具有热稳定性。使用拉曼光谱和紫外/可见光谱评估了PMS高效减水剂在不同水溶液中的碱性降解速率。在3年的时间里，使用上述任何一种分析方法在水解溶液中均未观察到变化。所得结果表明PMS聚合物具有良好的热稳定性和化学稳定性（在高碱性介质中，pH = 9.9 - 12.9）。
