The rheological properties of mortar samples with different additions of CO during mixing were determined. Flowable cement-based mortars at three different w/c (0.55, 0.45 and 0.35) were produced and the effects of CO gas were examined on the fresh properties of slump flow, yield stress and plastic viscosity. According to the experimental results, the mortar yield stress and plastic viscosity increased faster over time than in a reference system with the increasing addition of CO and greater effects were seen at the lowest w/c of 0.35 than at the others. The impact of the CO on the yield stress was more pronounced than on the viscosity. In the w/c 0.35 system the properties showed no effect at dosages of 0.06% and 0.13% CO by weight of cement. Increasing dosages to 0.19 and 0.25% resulted in an increasing reduction in slump flow, immediate increases in yield stress of 62 and 298%, increases in structural buildup by a factor of 5 and 10, respectively, and increased the initial plastic viscosity by 33 and 148%, respectively. The effects are attributable to the growth of reaction products decreasing the interparticle spacing and increasing the surface area as associated with the CaCO and gel phase. CO was demonstrated to be a potential yield stress control agent; an appropriate dose can increase rheological properties as measured immediately after and increase their rate of change with time. This aligns with specialized applications that hinge upon changing rheology such as form pressure control or 3D concrete printing.

中文翻译：

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CO2 流动砂浆的流变改性


测定了混合过程中添加不同 CO 的砂浆样品的流变特性。生产了三种不同水灰比（0.55、0.45 和 0.35）的可流动水泥基砂浆，并检查了 CO 气体对坍落流动、屈服应力和塑性粘度的新鲜性能的影响。根据实验结果，随着 CO 添加量的增加，砂浆的屈服应力和塑性粘度随着时间的推移比参考系统增加得更快，并且在最低 w/c 为 0.35 时效果比其他系统更大。 CO 对屈服应力的影响比对粘度的影响更明显。在 w/c 0.35 系统中，当 CO 用量为水泥重量的 0.06% 和 0.13% 时，性能没有表现出任何影响。将剂量增加到 0.19% 和 0.25% 会导致坍落度进一步降低，屈服应力立即增加 62% 和 298%，结构堆积分别增加 5 倍和 10 倍，初始塑性粘度增加 33 倍和 10 倍。分别为 148%。该效应可归因于反应产物的生长，减小了与 CaCO3 和凝胶相相关的颗粒间间距并增加了表面积。 CO 被证明是一种潜在的屈服应力控制剂；适当的剂量可以增加流变特性（如测量后立即测量）并增加其随时间的变化率。这与依赖于不断变化的流变学的专业应用相一致，例如成型压力控制或 3D 混凝土打印。