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

Gardner, Laura J.; Corkhill, Claire L.; Walling, Sam A.; Vigor, James E.; Murray, Claire; Tang, Chiu C.; Provis, John L.; Hyatt, Neil C.

doi:10.1016/j.cemconres.2021.106375

Cited by 45 publications

(20 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thermogravimetric analysis (TGA/DTG) of struvite-K (Figure A) revealed the occurrence of a single, significant mass loss (39.73%) between 40 and 200 °C. This event corresponds to the one-step dehydration of struvite-K (eq ) reported in the literature for both struvite-K , and magnesium potassium phosphate cements. − Differential thermal analysis (DTA) revealed that an endothermic event linked to the dehydration of struvite-K occurred between 150 and 200 °C (Figure B), confirming the one-step dehydration process. Beyond 200 °C, however, an exothermic event (with no mass loss; Figure B) was observed between 380 and 445 °C and centered at 405 °C in the DTA thermogram.…”

Section: Resultssupporting

confidence: 72%

Characterization of and Structural Insight into Struvite-K, MgKPO₄·6H₂O, an Analogue of Struvite

et al. 2020

Self Cite

View full text Add to dashboard Cite

Struvite-K (MgKPO4·6H2O) is a magnesium potassium phosphate mineral with naturally cementitious properties, which is finding increasing usage as an inorganic cement for niche applications including nuclear waste management and rapid road repair. Struvite-K is also of interest in sustainable phosphate recovery from wastewater and, as such, a detailed knowledge of the crystal chemistry and high-temperature behavior is required to support further laboratory investigations and industrial applications. In this study, the local chemical environments of synthetic struvite-K were investigated using high-field solid-state 25Mg and 39K MAS NMR techniques, alongside 31P MAS NMR and thermal analysis. A single resonance was present in each of the 25Mg and 39K MAS NMR spectra, reported here for the first time alongside the experimental and calculated isotropic chemical shifts, which were comparable to the available data for isostructural struvite (MgNH4PO4·6H2O). An in situ high-temperature XRD analysis of struvite-K revealed the presence of a crystalline–amorphous–crystalline transition that occurred between 30 and 350 °C, following the single dehydration step of struvite-K. Between 50 and 300 °C, struvite-K dehydration yielded a transient disordered (amorphous) phase identified here for the first time, denoted δ-MgKPO4. At 350 °C, recrystallization was observed, yielding β-MgKPO4, commensurate with an endothermic DTA event. A subsequent phase transition to γ-MgKPO4 was observed on further heating, which reversed on cooling, resulting in the α-MgKPO4 structure stabilized at room temperature. This behavior was dissimilar from that of struvite exposed to high temperature, where NH4 liberation occurs at temperatures >50 °C, indicating that struvite-K could potentially withstand high temperatures via a transition to MgKPO4.

show abstract

Section: Resultssupporting

confidence: 72%

Characterization of and Structural Insight into Struvite-K, MgKPO₄·6H₂O, an Analogue of Struvite

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…Magnesium potassium phosphate cements (MKPC) are receiving increasing interest for their use in a wide range of applications, including bone repair biomaterials [ 1 , 2 ], rapid repair of damaged concrete structures that require a short interruption of services, such as some highway pavement or airport runways [ 3 , 4 ], solidification of urban river dredged sludge [ 5 ], immobilization of galvanic wastes [ 6 ], stabilization and solidification of metals in a biodegradable matrix [ 7 ], 3D printing [ 8 , 9 , 10 ], and encapsulation of radioactive wastes [ 11 , 12 , 13 ].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2023

View full text Add to dashboard Cite

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.

show abstract

“…Nowadays, the MKPC can be used as a material for repair works because of its high bonding capacity, rapid setting, and high early strength [ 42 ]; it can also be used in the form of possible waste forms immobilizing and encapsulating galvanic waste and radioactive waste [ 43 , 44 , 45 ]. Moreover, MKPC can be used as a steel protective material for its corrosion and fire resistance [ 36 , 46 ].…”

Section: Introductionmentioning

confidence: 99%

Magnesium Potassium Phosphate Cement-Based Derivatives for Construction Use: Experimental Assessment

et al. 2022

View full text Add to dashboard Cite

The presented research is focused on the development and testing of the magnesium potassium phosphate cement-based materials (MKPC-based). Firstly, the fresh state properties of the pastes consisting of dead burned magnesia powder, potassium dihydrogen phosphate, setting retarder borax applied in the range of 0–10 wt.%, and batch water were investigated. The aim of testing was to characterize the hydration process in dependence on the borax content. The properties of raw MgO powder were described by chemical composition and particle size distribution. The properties tested in fresh state included shear stress (viscosity), Young’s modulus of elasticity, and temperature; their time dependence was observed. The measurements started immediately after the mixing process. At the age of 14 days, basic structural and mechanical properties of the hardened pastes were obtained. The mixture with 5 wt.% of borax proved to be the most advantageous in terms of setting time, sample integrity, and mechanical strength; therefore, it was chosen as the binder for the following part of the study—MKPC-based mortar development. In the next step, the MKPC paste containing 5 wt.% of borax was supplemented by silica sand aggregate, and the resulting material was marked as a reference. Subsequently, three other mixtures were derived by replacing 100% of quartz sand by lightweight aggregate; namely by expanded glass aggregate, waste rubber from tires, and combination of both in ratio 1:1. The aggregates were characterized by chemical composition (except for the rubber granulate), and loose and compacted powder density. For the resulting hardened composites, basic structural, hygric, strength, and thermal parameters were investigated. The use of lightweight aggregates brought in a considerable decrease in heat transport parameters and low water permeability while maintaining sufficient strength. The favorable obtained material properties are underscored by the fact that magnesia-phosphate is considered to be a low-carbon binder. The combination of magnesia-phosphate binder and recycled aggregate provides a satisfying, environmentally friendly, and thermally efficient alternative to traditional Portland cement-based materials.

show abstract

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

Cited by 45 publications

References 51 publications

Characterization of and Structural Insight into Struvite-K, MgKPO₄·6H₂O, an Analogue of Struvite

Characterization of and Structural Insight into Struvite-K, MgKPO₄·6H₂O, an Analogue of Struvite

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

Magnesium Potassium Phosphate Cement-Based Derivatives for Construction Use: Experimental Assessment

Contact Info

Product

Resources

About

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

Cited by 45 publications

References 51 publications

Characterization of and Structural Insight into Struvite-K, MgKPO4·6H2O, an Analogue of Struvite

Characterization of and Structural Insight into Struvite-K, MgKPO4·6H2O, an Analogue of Struvite

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

Magnesium Potassium Phosphate Cement-Based Derivatives for Construction Use: Experimental Assessment

Contact Info

Product

Resources

About

Characterization of and Structural Insight into Struvite-K, MgKPO₄·6H₂O, an Analogue of Struvite

Characterization of and Structural Insight into Struvite-K, MgKPO₄·6H₂O, an Analogue of Struvite