The study aimed to elucidate the mechanism behind rheological modification due to CO2 mixing at the mixing and post-mixing stages from an electrochemical perspective. The results indicated that CO2 mixing reduced the flowability while increasing penetration resistance and static yield stress. The electrostatic attraction between particles with opposite surface charges and the bridging effect of calcium carbonate constitute the primary factors for influencing the rheological properties of mortar at an early age. The altered surface charge of carbonized cement particles, primarily resulting from CO2 injection lowering the pH and ion concentration, reversed the zeta potential of particles from the traditionally negative charge (−3.59 mV) to a positive value (+13.3 mV). Furthermore, CO2 mixing further enhanced the dissolution of cement particles and accelerated the hydration process, thereby increasing the rate of structural build-up. CO2 mixing was demonstrated to be a potential rheological modifier for 3D-printed concrete applications.

中文翻译：

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CO2 混合对早期新砂浆流变学和电化学性能的影响


该研究旨在从电化学角度阐明 CO2 混合在混合和后混合阶段导致流变改性的机制。结果表明，CO2 混合降低了流动性，同时增加了渗透阻力和静态屈服应力。具有相反表面电荷的颗粒之间的静电吸引力和碳酸钙的桥接作用构成了影响砂浆早期流变性能的主要因素。碳化水泥颗粒的表面电荷改变，主要是由于 CO2 注入降低了 pH 值和离子浓度，使颗粒的 zeta 电位从传统的负电荷 （-3.59 mV） 反转为正值 （+13.3 mV）。此外，CO2 混合进一步增强了水泥颗粒的溶解并加速了水化过程，从而提高了结构堆积的速度。CO2 混合被证明是 3D 打印混凝土应用的潜在流变改性剂。