Diffusion dynamics in ecological concrete studied by neutron imaging method

The aim of this study is to investigate the diffusion process of gadolinium nitride solutions in light and heavy water with and without Gd3+ ions in a novel geopolymer mortar derived from red-clay bricks rubble for the nuclear waste encapsulation. Diffusion dynamics is studied by the neutron imaging method. A modern nuclear waste repository must prevent the escape of radionuclides into the environment. In the study presented by us, gadolinium ions were used due to their chemical similarity with radionuclides and large effective absorption cross section for thermal neutrons, providing thus excellent properties for neutron imaging. Due to the sensitivity of our neutron camera imaging system, we are in our best knowledge the first who report also on direct imaging of the diffusion of heavy water through the geopolymer mortar matrix. For the solutions used, the diffusion coefficients and diffusion rates are calculated by using the second Fick's law. The results obtained in this study are also of relevance for other areas of construction industry, helping in search for a more sustainable and environmentally friendly alternatives to conventional concrete.