Improving the Hydration and Carbonation of Reactive MgO Cement with Amino Acids and the Influencing Mechanisms

Low hydration and carbonation degree of reactive magnesium oxide cement (RMC) have always hindered the development of its properties. Motivated by the influence of amino acids on biomineralization, this work aimed to investigate the impacts of glutamic acid (Glu), serine (Ser), and arginine (Arg) on the hydration and carbonation of RMC under ambient-curing and accelerated CO 2 -curing. The exothermic hydration, mechanical strength, phase composition and thermal stability were studied. Results suggested that Glu significantly improved the compressive strength (0.1 M Glu increased strength by 58% at 14 days of accelerated CO 2 curing) and hydration degree (71% vs . 57%). The addition of amino acids varies the pH value of the system, and different effects of hydration and carbonation were observed among different amino acid-added samples. This effect can be attributed to the state of the amino acids in the solution at that pH. The negatively charged glutamic acid in the RMC system binds to Mg 2+ , leads to greater MgO dissolution, enhanced hydration and carbonation, and improved mechanical strength.