MgO-based cement offers a promising solution to lower the carbon footprint compared to that of Portland cement, where MgO is sourced from fossil-free minerals. The hydration of MgO plays a key role in these cements. However, MgO required higher water demand to achieve a workable mix, which poses drawbacks in microstructure and strength development. In this work, we investigated the effects of 7 polycarboxylate-based superplasticizers at different dosages on the fresh and hardened properties of MgO hydration. We found that some superplasticizers not only enhanced mix workability but also significantly increased compressive strength. The hydration, phase assemblage and evolution of MgO pastes using these superplasticizers were identical to those of the neat system, in which brucite formed as the primary hydration product. However, rheological evaluations demonstrated a marked reduction in yield stress and viscosity owing to the effects of superplasticizers. Furthermore, the addition of superplasticizer was found to improve the viscoelastic properties of the composites, as evidenced by an increase in critical shear strain and storage modulus. The insights gained from this research highlight the benefits of water-reducing additives in enhancing MgO reactivity and tailoring the formation of various MgO-bearing phases, such as magnesium carbonates or magnesium silicate hydrate, thereby facilitating more sustainable cement production.

中文翻译：

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聚羧酸醚减水剂存在下 MgO 水合的新见解

与波特兰水泥相比，MgO 基水泥提供了一种很有前途的解决方案，可以降低碳足迹，而波特兰水泥的 MgO 来自无化石矿物。MgO 的水化在这些水泥中起着关键作用。然而，MgO 需要更高的水需求才能实现可行的混合物，这在微观结构和强度发展方面存在缺点。在这项工作中，我们研究了 7 种不同剂量的聚羧酸盐基高效减水剂对 MgO 水合的新鲜和硬化性能的影响。我们发现，一些高效减水剂不仅提高了混合加工性，还显著提高了抗压强度。使用这些高效减水剂的 MgO 浆料的水化、相组装和析出与纯体系相同，其中水镁石形成为主要水化产物。然而，流变学评估表明，由于高效减水剂的作用，屈服应力和粘度显著降低。此外，发现添加高效减水剂可以改善复合材料的粘弹性，临界剪切应变和存储模量的增加证明了这一点。从这项研究中获得的见解强调了减水添加剂在增强 MgO 反应性和定制各种含 MgO 相（如碳酸镁或硅酸镁水合物）的形成方面的好处，从而促进更可持续的水泥生产。