Development of a stoichiometric magnesium potassium phosphate cement (MKPC) for the immobilization of powdered minerals

Campos, M. de; Davy, Catherine; Djelal, Nora; Rivenet, Murielle; Garcia, Justo

doi:10.1016/j.cemconres.2020.106346

Cited by 23 publications

(6 citation statements)

References 32 publications

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“…Previous works have demonstrated that the Mg/PO 4 molar ratio and the degree of humidity of the curing conditions are the main factors in the length change of MKPC, with the expected low impact of the filler in the MKPC system [ 42 ]. For the FA formulation, it was not possible to measure the dimensional stability due to the limited availability of this material in our study; nonetheless, results obtained by De Campos et al [ 44 ] for a similar formulation with the same water/cement and filler/cement ratios and curing conditions used in this work show a percentage of expansion of 0.1% after 28 days of curing.…”

Section: Resultsmentioning

confidence: 84%

Evaluation of Fillers for Magnesium Potassium Phosphate Cement (MKPC) for the Encapsulation of Low and Intermediate Level Metallic Radioactive Wastes

et al. 2023

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This study investigates the effect of coal fly ash (FA), wollastonite (WO), pumice (PM), and metakaolin (MK) as filler materials in the rheological, mechanical, chemical, and mineralogical properties of a magnesium potassium phosphate cement (MKPC), designed for the encapsulation of low and intermediate level radioactive wastes containing reactive metals. Workability, compression strength, dimensional stability, pH, chemical composition, and mineralogical properties were studied in different pastes and mortars of MKPC with a fixed molar ratio of MgO/KH2PO4 = 1. No new mineral phases were found with the addition of the fillers, denoting their low chemical impact on the MKPC system. Moreover, all formulations with a water/cement mass ratio of <0.65 presented compressive strengths higher than 30 MPa after 90 days, and pH values lower than 8.5, corresponding to the passivation zone of aluminum corrosion.

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Section: Resultsmentioning

confidence: 84%

Evaluation of Fillers for Magnesium Potassium Phosphate Cement (MKPC) for the Encapsulation of Low and Intermediate Level Metallic Radioactive Wastes

et al. 2023

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“…In recent years, practicability [ 13 , 14 , 15 , 16 ], new retarders [ 17 , 18 ], durability [ 19 , 20 ] and effects of new admixtures [ 18 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ] were focuses of research on MKPC. However, the hydration mechanism of MKPC has always been one of the key issues.…”

Section: Introductionmentioning

confidence: 99%

Effect of K+ Diffusion on Hydration of Magnesium Potassium Phosphate Cement with Different Mg/P Ratios: Experiments and Molecular Dynamics Simulation Calculations

Leng,

Fu,

et al. 2024

Materials

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Magnesium potassium phosphate cement (MKPC) is formed on the basis of acid–base reaction between dead burnt MgO and KH2PO4 in aqueous solution with K-struvite as the main cementitious phase. Due to the unique characteristics of these cements, they are suitable for special applications, especially the immobilization of radioactive metal cations and road repair projects at low temperature. However, there are few articles about the hydration mechanism of MKPC. In this study, the types, proportions and formation mechanism of MKPC crystalline phases under different magnesium to phosphorus (Mg/P) ratios were studied by means of AAS, ICP-OES, SEM, EDS and XRD refinement methods. Corresponding MD simulation works were used to explain the hydration mechanism. This study highlights the fact that crystalline phases distribution of MKPC could be adjusted and controlled by different Mg/P ratios for the design of the MKPC, and the key factor is the kinetic of K+.

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“…In recent years, magnesium phosphate cements (MPCs) have drawn a lot of interest for their ability to immobilize waste and, specifically, for the encapsulation of radioactive wastecontaining reactive metals, such as uranium, aluminium fuel cladding and magnesium alloys [6][7][8][9][10][11][12]. MPCs are characterized by their short setting time, high compressive strength, resistance to chemical attack, low pH and low shrinkage [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

“…At pH levels above 6.3, phosphorrösslerite (MgHPO 4 •7H 2 O) and a hydrated potassium magnesium phosphate (Mg 2 KH(PO 4 ) 2 •15H 2 O) are formed as intermediates. At pH levels below 6, newberyite (MgHPO 4 • 3H 2 O) is formed as an intermediate phase [10].…”

Section: Introductionmentioning

confidence: 99%

The Influence of the Magnesium-to-Phosphate Molar Ratio on Magnesium Potassium Phosphate Cement Properties Using Either Wollastonite or Volcanic Ash as Fillers

Padilla-Encinas,

Dieguez,

Cuevas

et al. 2024

Minerals

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The use of the fillers wollastonite and volcanic ash for the formulation of magnesium phosphate cements prepared at magnesium-to-phosphate molar ratios of 2, 3 and 4 has been investigated, with the objective of evaluating these formulations for the encapsulation of aluminium radioactive waste. The workability, mechanical strength, dimensional stability, pH, chemical composition and mineralogical properties of cement pastes and mortars were examined. All cement pastes presented fast setting, and the workability was only good at 3 and 4 M. The cement mortars presented high compressive strength and dimensional stability. K-struvite was confirmed as the sole reaction product of the reaction for all formulations. The pH of the cement pastes, measured in suspensions, achieved values in the range of 7.8 to 9.5 after the first days of setting, exceeding pH 8.5 for the 2 and 3 M formulations. pH values below 8.5 are theoretically preferred to avoid potential aluminium corrosion. Both fillers presented adequate characteristics (good workability, chemical compatibility) to be used in the formulation of magnesium phosphate cements. The increasing magnesium-to-phosphate molar ratio prevented unwanted efflorescence and increased the mechanical stability of the cement.

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Development of a stoichiometric magnesium potassium phosphate cement (MKPC) for the immobilization of powdered minerals

Cited by 23 publications

References 32 publications

Evaluation of Fillers for Magnesium Potassium Phosphate Cement (MKPC) for the Encapsulation of Low and Intermediate Level Metallic Radioactive Wastes

Evaluation of Fillers for Magnesium Potassium Phosphate Cement (MKPC) for the Encapsulation of Low and Intermediate Level Metallic Radioactive Wastes

Effect of K+ Diffusion on Hydration of Magnesium Potassium Phosphate Cement with Different Mg/P Ratios: Experiments and Molecular Dynamics Simulation Calculations

The Influence of the Magnesium-to-Phosphate Molar Ratio on Magnesium Potassium Phosphate Cement Properties Using Either Wollastonite or Volcanic Ash as Fillers

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