Reactive MgO cement (RMC) is a novel binder formed through the hydration and carbonation of MgO, but its low reactivity hinders its wider application. Preliminary research has suggested that citric acids can form compounds with Mg2+ that regulate these processes, but the mechanism is yet to be understood well. This study investigated the effects of citric acids on the fresh and hardened properties of RMC. Results showed that the shear yield stress and plastic viscosity of the RMC pastes decreased with the addition of citric acids. Under standard curing, 4 wt% and 8 wt% citric acids increased the compressive strength of RMC by ∼100 % at 14 days. The adsorption of citrate on MgO inhibited the formation of brucite, forming an amorphous network-like microstructure crystallised after 14 days. Under CO2 curing, the compressive strength of RMC with 8 wt% citric acids increased by 12 % at 14 days, which could be ascribed to the porous microstructure formed that promotes the uptake of CO2 and the densification of the microstructure.

中文翻译：

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柠檬酸调控活性 MgO 水泥的水化和微观结构发育


活性 MgO 水泥 （RMC） 是一种通过 MgO 水化和碳化形成的新型粘合剂，但其低反应性阻碍了其更广泛的应用。初步研究表明，柠檬酸可以与 Mg2+ 形成调节这些过程的化合物，但其机制尚未得到很好的理解。本研究调查了柠檬酸对 RMC 新鲜和硬化特性的影响。结果表明，随着柠檬酸的加入，RMC 浆料的剪切屈服应力和塑性黏度降低。在标准固化下，4 wt% 和 8 wt% 柠檬酸在 14 天时将 RMC 的抗压强度提高了 ∼100 %。柠檬酸盐在 MgO 上的吸附抑制了水镁石的形成，在 14 天后形成无定形网状微观结构结晶。在 CO2 固化下，含有 8 wt% 柠檬酸的 RMC 在 14 天时提高了 12 %，这可能归因于形成的多孔微观结构促进了 CO2 的吸收和微观结构的致密化。