Magnesium oxysulfates (MOS), obtained by hydration of MgO in MgSO4 solution, are highly interesting as binders in lightweight building materials due to their environmental sustainability and promising technological properties. Recent focus has been concentrated on tailoring the phase composition towards 5Mg(OH)2·MgSO4·7H2O (517 phase) by using various additives (e.g. citric acid) that generally act as retarders of the direct hydration of Mg(OH)2, a competing phase in this system. In this work, macromolecules of vegetal origin were investigated as possible retarders to promote the crystallization of the 517 phase. Isothermal and semi-adiabatic hydration experiments were performed, together with thorough microstructural investigations of hardened cements by electron microscopy techniques (SEM, TEM) as well as X-ray powder diffraction and quantitative phase analyses by Rietveld refinements. The results show a temperature and time dependent retardant effect that is only effective in promoting the crystallization of the 517 phase at ambient temperature. Implications for the manufacturing of lightweight concrete are discussed.
Hydration kinetics and microstructural development of a magnesium oxysulfate cement modified by macromolecules / Barbieri, V.; Lassinantti Gualtieri, M.; Manfredini, T.; Siligardi, C.. - In: CONSTRUCTION AND BUILDING MATERIALS. - ISSN 0950-0618. - 248:(2020), pp. 118624-118624. [10.1016/j.conbuildmat.2020.118624]
Hydration kinetics and microstructural development of a magnesium oxysulfate cement modified by macromolecules
Barbieri V.
;Lassinantti Gualtieri M.Membro del Collaboration Group
;Manfredini T.Membro del Collaboration Group
;Siligardi C.Supervision
2020
Abstract
Magnesium oxysulfates (MOS), obtained by hydration of MgO in MgSO4 solution, are highly interesting as binders in lightweight building materials due to their environmental sustainability and promising technological properties. Recent focus has been concentrated on tailoring the phase composition towards 5Mg(OH)2·MgSO4·7H2O (517 phase) by using various additives (e.g. citric acid) that generally act as retarders of the direct hydration of Mg(OH)2, a competing phase in this system. In this work, macromolecules of vegetal origin were investigated as possible retarders to promote the crystallization of the 517 phase. Isothermal and semi-adiabatic hydration experiments were performed, together with thorough microstructural investigations of hardened cements by electron microscopy techniques (SEM, TEM) as well as X-ray powder diffraction and quantitative phase analyses by Rietveld refinements. The results show a temperature and time dependent retardant effect that is only effective in promoting the crystallization of the 517 phase at ambient temperature. Implications for the manufacturing of lightweight concrete are discussed.
Pubblicazioni consigliate
I metadati presenti in IRIS UNIMORE sono rilasciati con licenza Creative Commons CC0 1.0 Universal, mentre i file delle pubblicazioni sono rilasciati con licenza Attribuzione 4.0 Internazionale (CC BY 4.0), salvo diversa indicazione.
In caso di violazione di copyright, contattare Supporto Iris
