Reactive MgO (rMgO) is considered a promising alternative to Portland cement (PC), because its capacity to mineralize carbon dioxide (CO₂) can be used to reduce the life cycle global warming intensity (GWI) of concrete. However, the greenhouse gases (GHG) emitted during the manufacture of rMgO may outshine its environmental benefits of CO₂ mineralization. The objective of this study is to compare the life cycle GWI of traditional PC binder to rMgO binder and rMgO-PC blended binder systems. The life cycle assessment (LCA) considers the actual amount of CO₂ mineralized by the binders and their 28-day compressive strength, as well as different manufacturing routes (dry and wet) and energy sources (fossil fuels and electricity) to produce rMgO. Based on these variables, best- and worst-case scenarios were identified and analyzed. The results reveal that the quantity of CO₂ stored in hydrated Mg carbonates increases as the rMgO replacement level increases, while the quantity of CO₂ stored in Mg-calcite decreases. Mortar with rMgO-PC as binder exhibits a lower net GWI per unit of strength than mortars with either 100% PC or 100% rMgO as binder in the best-case scenarios. Using low carbon energy sources (such as renewables and nuclear) for rMgO production and on-site waste CO₂ would significantly reduce the overall GHG emissions (by 82%). In the optimal situation, a net GWI reduction of almost 50% per unit of strength can be achieved by the rMgO-PC mortar. The wet route to produce rMgO looks particularly promising for a future decarbonized construction sector since no CO₂ is chemically released during its manufacture. The properties and GWI of concrete containing rMgO carbonated in flowing CO₂-rich gas warrant future study.

反应性 MgO (rMgO) 被认为是波特兰水泥 (PC) 的有前景的替代品，因为其矿化二氧化碳 (CO ₂ ) 的能力可用于降低混凝土的生命周期全球变暖强度 (GWI)。然而，rMgO 制造过程中排放的温室气体 (GHG) 可能会超过其 CO ₂矿化的环境效益。本研究的目的是比较传统 PC 粘合剂与 rMgO 粘合剂和 rMgO-PC 混合粘合剂系统的生命周期 GWI。生命周期评估 (LCA) 考虑 CO ₂的实际量通过粘合剂及其 28 天的抗压强度以及不同的制造路线（干和湿）和能源（化石燃料和电力）矿化以生产 rMgO。基于这些变量，确定和分析了最佳和最坏情况。结果表明，CO的量₂存储在水合镁碳酸盐随着rMgO替代水平的增加，而CO的量₂存储在镁方解石减小。在最佳情况下，使用 rMgO-PC 作为粘合剂的砂浆每单位强度的净 GWI 低于使用 100% PC 或 100% rMgO 作为粘合剂的砂浆。使用低碳能源（如可再生能源和核能）生产 rMgO 和现场废物 CO ₂将显着减少总体温室气体排放量（减少 82%）。在最佳情况下，rMgO-PC 砂浆可以实现每单位强度的净 GWI 降低近 50%。生产 rMgO 的湿法路线对于未来的脱碳建筑行业看起来特别有前途，因为在其制造过程中不会化学释放CO ₂。在流动的富含 CO _{2 的}气体中含有碳酸化 rMgO 的混凝土的性能和 GWI值得进一步研究。