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

Abstract

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.