Abstract In France, IER solidification processes, by embedding into polymer based matrices, are operated at the industrial scale. The CEA process utilizes the epoxide resin as IER embedding matrix, with an embedding ratio equal to 0.5. A new embedding process was studied, using an epoxide cement compound matrix, with an embedding ratio 0.4. On this new material and IER embedded forms, an external gamma irradiation test was carried out, using a Cobalt 60 irradiator, called IRCA, until absorption of a 3 MGy integrated gamma dose. The effects of the gamma radiolysis were measured and the results compared to those obtained on IER epoxide embedded forms. The radiolytic gas production, dimensional changes and other secondary effects are discussed.