Abstract This study investigated the formation of different phases and their influence on the microstructural and mechanical development of carbonated reactive MgO cement formulations. Hydrated magnesium carbonates (HMCs) were identified and quantified via XRD, TG-DTG and SEM. Visual observations of the 3D internal structure at different depths were performed by X-ray computed tomography and confocal Raman microscopy. Elastic modulus of different components was obtained by nano-indentation. The expansive formation of HMCs led to dense microstructures composed of well-connected carbonate networks. The transition of artinite to hydromagnesite/nesquehonite was observed over time. The initial formation of a dense carbonate layer on sample surface inhibited continuous diffusion of CO2, resulting in a slower strength development at later ages. Despite this limitation, the continuation of hydration and evolution of carbonate morphology led to 28-day strengths of 60 MPa in concrete samples, supported by the higher elastic modulus of HMCs than brucite (19.4 vs. 2.5 GPa).

中文翻译：

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碳酸盐相的形成及其对活性氧化镁水泥配方性能的影响

摘要 本研究调查了不同相的形成及其对碳酸化活性氧化镁水泥配方的微观结构和机械发展的影响。通过 XRD、TG-DTG 和 SEM 鉴定和量化了水合碳酸镁 (HMC)。通过 X 射线计算机断层扫描和共聚焦拉曼显微镜对不同深度的 3D 内部结构进行目视观察。通过纳米压痕获得不同组分的弹性模量。HMC 的膨胀形成导致由连接良好的碳酸盐网络组成的致密微结构。随着时间的推移，观察到铝镁石向水菱镁矿/三水菱镁矿的转变。样品表面最初形成的致密碳酸盐层抑制了 CO2 的持续扩散，导致后期强度发展缓慢。