Carbonation curing influencing factors of Carbonated Reactive Magnesia Cements (CRMC) – A review

Understanding the role of seeds in reactive magnesia cement (RMC) formulations

“…Moreover, as shown in Figure 11(B), Part B (internal), Part C 1 (external), and C 2 (external) represent different sections of RMC samples, which is in agreement with the easiness of CO 2 diffusion among different regions of RMC samples, resulting from the higher HMCs amount formed on the surface. As a result, the porosity on the surface of RMC samples was reduced, hindering further CO 2 diffusion into the deeper part of the samples, which is in line with the reference 8 . Thereby, the interior carbonation degrees of RMC samples were much lower than that on the external sections, which was verified by the porosity differences among Part B, Part C 1 , and Part C 2 .…”

“…Furthermore, when it comes to the same group, in comparison with interior regions, the hydration degree is higher in exterior regions, as revealed by their lower content in un‐hydrated MgO. The greater hydration degree in exterior regions was related to reduced pH, resulting from the easiness of more CO 2 diffusion in exterior regions of samples 8 . As a result, the hydration of MgO was enhanced.…”

“…A schematic illustration of the EDL and the formation of zeta‐potentials in the model RMC solution are shown in Figure 4, as adapted from the OPC system 21 . Mg 2+ , OH − , and CO 3 2− are the main elements in the pore solution of the RMC system 8 . SO4 2− ions have been adopted to prepare the model solution of C‐S‐H system 22 and do not form precipitates with Mg 2+ ions.…”

“…In a series of applications, reactive MgO cement (RMC) 1–3 is gaining growing interest as it can be an alternative to ordinary Portland cement (OPC), 4,5 and using RMC reveals two benefits: (1) the lower energy consumption due to its lower calcination temperature than OPC 6–9 ; (2) its great CO 2 sequestration potential that could store CO 2 permanently 10–12 . However, due to the very limited strength gained by brucite (the hydration phase of MgO) in an ambient environment, 13 accelerated carbonation has been introduced to enhance the mechanical performances of RMC‐based samples, which is through the reaction between brucite and CO 2 so that hydrated magnesium carbonates (HMCs) could form such as nesquehonite (MgCO 3 ⋅3H 2 O) and hydromagnesite (4MgCO 3 ⋅Mg(OH) 2 ⋅4H 2 O) 8 . On that account, the formed HMCs could provide dense microstructures and strong microstructural strength, leading to the overall strength development of RMC‐based samples 7 …”

Marine Sponge-Inspired Organic–Inorganic Double-Network Strategy to Produce Magnesium Oxychloride Cement with Integrated Water Resistance and Compressive Strength

“…As a major carbon emission, energy intensity, and resource depletion contributor, the ordinary portland cement production industry is responsible for endangering the environmental stability. − Hence, the development of alternative, environmental friendly, and sustainable cementitious materials for cleaner production have received considerable attention. In particular, magnesium oxychloride cement (MOC) has attracted extensive interests due to the low carbon footprint, effective resistance to abrasion, good durability, low alkalinity, and excellent cohesiveness, suggesting potential uses in various applications. − In the ternary system (MgO–MgCl 2 –H 2 O) of MOC, MgCl 2 is the major waste and byproduct of the potash industry .…”