Mechanisms of k-struvite formation in magnesium phosphate cements

Rouzic, Mathieu Le; Chaussadent, Thiérry; Platret, Gérard; Stéfan, Lavinia

doi:10.1016/j.cemconres.2016.11.008

Cited by 150 publications

(54 citation statements)

References 17 publications

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“…In fact, it is plausible that, in diluted systems, leaving the kinetic path, the reaction follows a different mechanism. The crystallization of metastable intermediate phases at high water contents (w/s ratios between 5 and 100) [16,[20][21][22] agrees with this view. For water contents in the range covered in the present experiment, after 30 min MKP was the only crystalline product detected [16,22], as confirmed by the obtained X-ray powder diffraction (Online Resource 2) and SEM results.…”

Section: Discussionsupporting

confidence: 78%

“…In this view should also be intended the use of a wide range of w/s ratio. As already showed, formulations with very different water contents may help to gain insights into the process leading to the development of properties in this class of ceramics [16,[19][20][21][22][23].…”

Section: Discussionmentioning

confidence: 92%

“…1; a lower content would leave a fraction of unreacted reagents and any excess should be segregated in pores within the volume. Studies on pastes and suspensions with large water contents have been frequently reported [16,[19][20][21][22], and Mg-P-based materials with excess of water have been considered for specific applications, like in the fabrication of injectable biomedical cements [23] (w/s up to 1). However, detailed characterization of the role of water in defining the microstructure in MPC is lacking.…”

Section: Introductionmentioning

confidence: 99%

“…In general, it is of practical importance to verify the role of water on the development of the coarse microstructure of MPCs (up to mm in pore size), because it may help to shed light on the reaction mechanisms, and, ultimately, help in product design. In fact, different reaction sequences have been reported in function of MPC formulation [16,20,22,26]. There is indication that this occurs in reason of the degree of supersaturation achieved in solution in the first stages of the reaction.…”

Section: Introductionmentioning

confidence: 99%

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3D microstructure of magnesium potassium phosphate ceramics from X-ray tomography: new insights into the reaction mechanisms

et al. 2018

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Magnesium potassium phosphate ceramics are chemically bonded ceramics employed as biomaterials, in nuclear waste encapsulation and for concrete repair. The microstructure dictates material performance and depends on the raw mix composition. Synchrotron X-ray computed microtomography was employed to describe the 3D microstructure and its time evolution during hardening and gain insights into the reaction mechanisms. Any excess water with respect to the stoichiometry of the reaction brought about an increase in porosity, but, notably, a reduction in the average pore size. Crystals filled the water 'pockets' in the ceramic volume by growing larger, although less densely packed, increasing the complexity of the pore shape. Platelet over elongated crystal habit was favoured. Such a change in shape is likely related to a change in reaction mechanism, as crystallization from a gel-like amorphous precursor is hindered and progressively substituted by a through-solution mechanism. It is proposed that the time evolution of the microstructure is dictated by the balance between crystallization from amorphous precursor, prevailing in relatively 'dense' systems (with stoichiometric water or in low excess), and water segregation, prevailing at higher water contents. The former mechanism was shown to produce an increase in porosity with time, because of the density mismatch between the amorphous and the crystalline phase.

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Section: Discussionsupporting

confidence: 78%

Section: Discussionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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3D microstructure of magnesium potassium phosphate ceramics from X-ray tomography: new insights into the reaction mechanisms

et al. 2018

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“…This phenomenon is due to the crystallization, which takes place on the cement matrix of mortars [34][35][36]. The crystallization effect is more noticeable on formulations without AEA because their porosity is lower as well as a higher densification of the mortar is allowed.…”

Section: Modulus Of Elasticitymentioning

confidence: 99%