Early age hydration and application of blended magnesium potassium phosphate cements for reduced corrosion of reactive metals

Magnesium potassium phosphate cements (MKPC) were investigated to determine their efficacy towards retardation of reactive uranium metal corrosion. Optimised low-water content, fly ash (FA) and blast furnace slag (BFS) blended MKPC formulations were developed and their fluidity, hydration behaviour, strength and phase assemblage investigated. In-situ time resolved synchrotron powder X-ray diffraction was used to detail the early age (similar to 60 h) phase assemblage development and hydration kinetics, where the inclusion of BFS was observed to delay the formation of struvite-K by similar to 14 h compared to FA addition (similar to 2 h). All samples set within this period, suggesting the possible formation of a poorly crystalline binding phase prior to struvite-K crystallisation. Longterm corrosion trials using metallic uranium indicated that MKPC systems are capable of limiting uranium corrosion rates (reduced by half), when compared to a UK nuclear industry grout, which highlights their potential application radioactive waste immobilisation.

Automated summary

The study found that Magnesium potassium phosphate cements (MKPC) can effectively retard the corrosion of reactive uranium metal. Optimized formulations of MKPC with low water content, fly ash (FA) and blast furnace slag (BFS) showed good fluidity, strength and phase assemblage. In-situ time resolved synchrotron powder X-ray diffraction revealed that the inclusion of BFS delayed the formation of Struvite-K, and MKPC systems have the potential application in limiting uranium corrosion rates.