Temperature transformation of blended magnesium potassium phosphate cement binders

In this study, a multi-technique approach was utilised to determine the high temperature performance of magnesium potassium phosphate cement (MKPC) blended with fly ash (FA) or ground granulated blast furnace slag (GBFS) respect nuclear waste immobilisation applications. Conceptual fire conditions were employed (up 1200 °C, 30 min) simulate scenarios that could occur during interim storage, transportation within final geological disposal facility. After exposure up 400 main crystalline phase, struvite-K (MgKPO4·6H2O), dehydrated poorly MgKPO4 (with corresponding volumetric and mass changes), recrystallisation achieved by 800 °C. XRD SEM/EDX analysis revealed reaction occurred between FA/GBFS components after 1000–1200 formation aluminosilicate phases, leucite kalsilite (KAlSi2O6 KAlSiO4), commensurate reduced relative intensity (or complete elimination) MgKPO4. This further supported solid-state NMR (27Al 29Si MAS), where only residual features associated raw observable at The phase transformation MKPC binders resulted in development glass/ceramic matrix all existing porosity infilled via sintering vitreous whilst physical integrity retained (no cracking spalling). study demonstrates that, based on small-scaled specimens, should perform satisfactorily under parameters relevant operation facility, least