Characterization of Mg components in reactive MgO – Portland cement blends during hydration and carbonation. (October 2018)

• Record Type: Journal Article
• Authors: Zhang, Runxiao; Bassim, Nabil; Panesar, Daman K.
• Is Part Of: Journal of CO₂ utilization. Volume 27(2018)
• Page Start: 518
• Page End: 527
• Publication Date: 2018-10
• Subjects: Reactive MgO -- Accelerated carbonation -- Hydration -- Amorphous hydrated Mg carbonate; Carbon dioxide -- Periodicals; Carbon dioxide -- Environmental aspects -- Periodicals; Carbon dioxide mitigation -- Periodicals; Carbon dioxide; Carbon dioxide -- Environmental aspects; Carbon dioxide mitigation; Periodicals; 628.53205
• DOI: 10.1016/j.jcou.2018.08.025
• Languages: English
• ISSNs: 2212-9820

Abstract

Highlights: This study examines Mg components formed by hydration and carbonation in r-MgO and PC blends. Nesquehonite only occurs in the carbonated r-MgO-PC paste with r-MgO replacement ≥ 60%. An amorphous phase of hydrated Mg carbonate was identified. hydrotalcite and magnesium silicate hydrate are major hydration products of 30–40% r-MgO paste. Abstract: A carbonated binder system containing reactive MgO (r-MgO) and Portland cement (PC) has the potential to provide sufficient mechanical properties and reduce carbon the footprint. However, the understanding of the chemistry of hydration and carbonation of the r-MgO-PC system remains unclear. The purpose of this study is to characterize the Mg components that form blends of r-MgO and PC during hydration and carbonation. Paste specimens of r-MgO and PC with r-MgO replacement levels from 10% to 90% were cast, carbonated and examined. Experimental observations reveal that: (1) nesquehonite only occurs in the carbonated r-MgO-PC paste with r-MgO replacement ≥ 60%; (2) an amorphous phase of hydrated Mg carbonate was identified in the carbonated paste with 50% r-MgO replacement; and (3) hydrotalcite and magnesium silicate hydrate are major hydration products of r-MgO during the hydration of the paste containing 30% and 40% r-MgO, which are expected to be the precursors of amorphous hydrated Mg carbonate.