• Magnesium phosphate cements (MKPCs) are positioning as good candidates for the immobilisation of low and intermediate radioactive waste. These cements set and harden via acid-base reaction between a MgO and a KH2PO4, to form as main reaction product K-Struvite. Among its advantages, include the rapid strength development at early ages, good volume stability and low water demand. • The present work explores the effect of incorporating spent ion exchange resins (SIERs), doped with Cs, in magnesium phosphate cements (MKPC), prepared with a low-grade MgO (58 % MgO). For this purpose, different proportions of the Cs-doped resin (0, 10, 15 and 20 wt.%) were added into MKPC pastes (prepared with an M/P molar ratio of 3). At different time intervals (1, 7 and 28d), compressive strengths were tested. The effect of resins on the kinetic of reaction, the mineralogy (XRD) and the microstructure (MIP, BSEM /EDX) were also determined. • The results obtained show that the incorporation of resins retards the kinetic of reaction, decreases the mechanical strength development and affects the microstructure (increasing the total porosity values). However, all systems, including those with the highest proportion of SIERs (20%), overpass the 10 MPa (waste acceptance criteria) after 28 days of curing. The presence of resin does not seem to affect formation of K-Struvite

2nd International Confernece of Innovation in Low Carbon Cement and Concrete Technology, Londres, UK. 8-11 July 2024

Peer reviewed