Mechanical and thermal properties of concrete suitable for radioactive waste disposal sites

Abstract

Secondary casing as a part of a multi-barrier system serves to meet the safety requirements on the radioactive waste repositories. Such casing needs to be durable, radiation- and thermal resistant, with good mechanical properties; these requirements are fulfilled by concrete. However, the casing should also serve as a barrier limiting the leaching of radionuclides, in case of failure of primary package. This problem is addressed in the article by the addition of a sorption material (natural zeolite rock) in the concrete mixture. Mechanical and thermal properties of concrete containing different amount of natural zeolite rock are studied with the link to concrete porosity. The addition of natural zeolite is found to cause a decrease in thermal conductivity and specific heat capacity. Both compressive and flexural strength decrease as well when natural zeolite is added in the mixture, which correlates with the increase of open porosity of studied concrete mixtures.