Evolution of phase assemblage of blended magnesium potassium phosphate cement binders at 200° and 1000°C

Abstract

The fire performance of magnesium potassium phosphate cement (MKPC) binders blended with fly ash (FA) and ground granulated blast furnace slag (GBFS) was investigated up to 1000°C using X-ray diffraction, thermogravimetric analysis and SEM techniques. The FA/MKPC and GBFS/MKPC binders dehydrate above 200°C to form amorphous KMgPO₄, concurrent with volumetric and mass changes. Above 1000°C, additional crystalline phases were formed and microstructural changes occurred, although no cracking or spalling of the samples was observed. These results indicate that FA/MKPC and GBFS/MKPC binders are expected to have satisfactory fire performance under the fire scenario conditions relevant to the operation of a UK or other geological disposal facility

Keywords:

• MKPC
• Fly ash
• Ground granulated blast furnace slag
• Fire performance
• Nuclear waste

Acknowledgements

LJG is grateful to the Nuclear Decommissioning Authority for sponsorship, under administration by the National Nuclear Laboratory. NCH wishes to acknowledge the Royal Acad-emy of Engineering, the Nuclear Decommissioning Authority and EPSRC for funding support (grant no. EP/L014041/1). CLC is grateful to the University of Sheffield for the award of a Vice Chancellor's fellowship. This research was performed in part at the MIDAS Facility, at the University of Sheffield, which was established with support from the Department of Energy and Climate Change.