Analysis of the influence of the aluminosilicate sorbents on the immobilization of ¹³⁷Cs in the cement compound and its mechanical strength

Studies have been carried out to determine the main parameters characterizing the quality of cement compounds: ¹³⁷Cs leaching rate and mechanical strength. As sorption additives, aluminosilicate sorbents were used, obtained from clay-salt slimes of JSC “Belaruskali” as a result of water and acid-water treatment to increase the content of the clay mineral illite, which is the main component in the composition of aluminosilicate sorbents. Model aqueous solutions of ¹³⁷Cs were used as liquid radioactive waste, including those with a NaNO₃ content of 150 g/dm . It has been established that the use of aluminosilicate sorbents makes it possible to reduce the rate of ¹³⁷Cs leaching from cement compounds, which indicates a higher degree of ¹³⁷Cs fixation in the matrix material compared to samples of cement compounds without sorption additives. The efficiency of the aluminosilicate sorbent for ¹³⁷Cs immobilization during cementation of a model solution of liquid radioactive waste is 3 times higher than the well-known and widely used sorption additive (bentonite clay from the 10th Khutor deposit, Khakassia, Russia). Determination of the mechanical strength of samples of cement compounds with the addition of 5–15 % aluminosilicate sorbents showed that this indicator is 8–9 times higher than the standard value (4.9 MPa). The optimal dose of a sorption additive is 5–10 wt.% of the weight of Portland cement, which does not cause a significant decrease in the strength of the cement compound compared to a compound without the use of an additive and, at the same time, will provide a high level of ¹³⁷Cs immobilization. The obtained research results indicate the prospects of using the developed aluminosilicate sorbents as a sorption additive for ¹³⁷Cs immobilization when handling liquid radioactive waste.

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