Modification of magnesium hydroxide for improved performance in CO2 sequestration

Abstract

Magnesium hydroxide (Mg(OH)2) can gain strength through carbonation, presenting a potential for its use as a cementitious component. This study proposes a novel method to increase the reactivity and carbonation performance of Mg(OH)2 via the use of acetate-based solution as modifier, which was recovered and reused repeatedly. Modification improved the microstructure and reactivity of Mg(OH)2, increasing the carbonation degree and compressive strength. After 7 days of carbonation curing, the compressive strength of modified Mg(OH)2 pastes was about twice that of unmodified Mg(OH)2 pastes (24.6 vs. 12.9 MPa). The interaction between modifiers and Mg(OH)2 enabled the increased dissolution of Mg(OH)2 and subsequent carbonation reaction. The differences in the reactivity of modified and unmodified Mg(OH)2 led to variations in their carbonation products. The differences in the morphology of the observed carbonation products could further affect the carbonation process. The findings of this study could pave the way enabling the use of Mg(OH)2 as a cementitious binder, meanwhile providing permanent CO2 sequestration within building components.