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ST 4.3 –
Gestión de residuos radiactivos
STUDY OF COMMERCIAL CHEMICAL ADDITIVES FOR
CEMENTATION OF RADIOACTIVE WASTE
Mota Vieira, Vanessa*; Oliveira de Tello, Clédola Cássia
Centro de Desenvolvimento da Tecnologia Nuclear (CDTN). Brazil.
* Responsible author, email: vanessamotavieira@gmail.com
Cementation is a very useful process to solidify radioactive wastes. Depending on the waste it
can be necessary the use of chemical admixtures to improve the cementation process and its
product. Admixtures are materials, other than cement, aggregate and water, that are added
either before or during the mixing to alter some properties, such as workability, curing
temperature range, and setting time. However there are a large variety of these materials that
are frequently changed or taken out of the market. In this changeable scenario it is essential to
know the commercially available materials and their characteristics. In this research the effects
of chemical admixtures in the solidification process has been studied. For the tests it was
prepared a solution simulating the evaporator concentrate waste, cemented by two different
formulations, and three chemical admixtures from two manufacturers. The tested admixtures
were setting accelerators, setting retarders and superplasticizers. The experiments were
organized by a factorial planning 23 to quantify the effects of formulations, of the admixtures, its
quantity and manufacturer in properties of the paste and products. The measured parameters
were the density, the viscosity and the setting time of the paste, and the product compressive
strength. The parameter evaluated in this study was the compressive strength at 28 days of
age, which is considered an essential security issues relating to the handling, transport and
storage of cemented waste product. The results showed that the addition of accelerators
improved the compressive strength of responses.