[en] This final report is devoted to the selection of additive-cement mixtures which could be used for cesium retention in the case of 300 g/l sodium nitrate waste embedment. Different types of additive are tested, mainly sodium and calcium smectites, TUBAC pozzolan, silica fume and calcium hexacyanoferrate, together with the three principal cements known in France: Portland cement, Pozzolanic (CLC) and high Alumina cement. Adsorption-desorption capacities of these different additive-cement mixtures with and without sodium nitrate are evaluated. Three solutions are considered to improve cesium retention in the case of sodium nitrate embedment: (1) hexacyanoferrate with Alumina cement (precipitation of (Ca, Cs) ferrocyanide, insoluble at high pH), (2) sodium smectite with silica fume and CLC, (3) sodium smectite wiht silica fume and Portland cement. These two last additives are complementary: Na-smectite exchanges sodium with cesium at the early stages of mixture and silica fume fills up intergranular spaces and decreases the pH of the interstitial pore water