Cementitious materials are widely used in the nuclear industry for the conditioning of radioactive waste. In this context, a study of the cementation of the spent radioactive resins in the presence of an addition consisting of natural red clay was carried out. The essential goal is to increase the quantity of confined resins without altering the final cemented resins form. The materials used including the spent resins and local red clay were characterized, the cemented resins form were carried out by mixing 16.12 % of water, 53 % of Portland cement class 45, (16.504 %.- X %) of Sand, (X %) of red clay with X between 0 and 10 %, and 14.38 % of spent resins. The characterization of cemented resins forms were completed by X-ray fluorescence, by X-Ray diffraction spectrometry and by Scanning Electron Microscope. The mechanical quality of each cemented resins forms was determined after 28 days of curing, by measuring the compressive strength and analysing its porosity. The cemented waste forms made by substituting 2 % and 4 % of sand with local red clay gave interesting results. The value of their compressive strength being equal to 18.4 MPa. The porosity is 33.91 %, Moreover, the analysis of the XRD spectra showed that the formulation at 4 % is the richest in C-S-H. Compared to the reference cemented resins forms carried out in the absence of red clay, the two cemented waste forms have 45 % higher compressive strength, with an improvement in their porosity. Under these conditions, the quantity of confined resin recorded an increase of 14.4 %