Early age hydration and application of blended magnesium potassium phosphate cements for reduced corrosion of reactive metals. (May 2021)

• Record Type: Journal Article
• Authors: Gardner, Laura J.; Corkhill, Claire L.; Walling, Sam A.; Vigor, James E.; Murray, Claire A.; Tang, Chiu C.; Provis, John L.; Hyatt, Neil C.
• Is Part Of: Cement and concrete research. Volume 143(2021)
• Publication Date: 2021-05
• Subjects: Chemically bonded ceramics (D) -- Calorimetry (A) -- Hydration (A) -- X-ray diffraction (B) -- Radioactive waste (E); Cement -- Periodicals; Cement -- Research -- Periodicals; Concrete -- Periodicals; Concrete -- Research -- Periodicals; Ciment -- Périodiques; Béton -- Périodiques; Cement; Concrete; Periodicals; 620.135
• DOI: 10.1016/j.cemconres.2021.106375
• Languages: English
• ISSNs: 0008-8846

Abstract

Abstract: 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 (~60 h) phase assemblage development and hydration kinetics, where the inclusion of BFS was observed to delay the formation of struvite-K by ~14 h compared to FA addition (~2 h). All samples set within this period, suggesting the possible formation of a poorly crystalline binding phase prior to struvite-K crystallisation. Long-term 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. Graphical abstract: Unlabelled Image Highlights: Magnesium potassium phosphate cements were studied for nuclear waste encapsulation. The optimised formulation in this study was determined to be 0.24 w/s ratio. Different reaction kinetics were discovered for the FA/MKPC and BFS/MKPC binders. Struvite-K was the only crystalline reaction product observed via in-situ SXPD. Uranium trials revealed MKPC corrosion was reduced compared to a UK nuclear grout.