Construction and demolition (C&D) waste has caused various economic, environmental, and social problems. This paper investigates the potential of recycled concrete fine powder (RFP) as a supplementary cementitious material. The effect of RFP with different replacement levels on the properties of cement and the mechanism of action were explored from the physical characteristics, mechanical properties, hydration kinetics, hydration products, and pore structure. In this study, scanning electron microscopy, Energy Dispersive X-Ray Spectroscopy, X-ray diffraction, X-ray fluorescence, Thermogravimetric analysis, and Isothermal calorimeter were applied. The results showed that RFP (less than 30%) shortened the setting time and improved the fluidity of cement. The early compressive strength increased by 17.62% of the cement mortar with 10% RFP. When the RFP content was 10%, the flowability of the blended slurry (175.5 mm) increased by 8.0% compared to the pure cement (162.5 mm). With the RFP content increase of the blended cement, the hydration induction period was prolonged, and the peak hydration exothermic rate and the accumulated heat release showed an apparent decreasing trend. The reaction rate of the nucleation and crystal growth (NG) process was much higher than that of the interface (I) and diffusion (D) processes. The low field nuclear magnetic resonance (NMR) technique revealed that RFP filled the large and medium pores of the mortar. The non-destructive layered scanning found that the pores were distributed mainly in the central zone and had a gradient distribution law of gradually decreasing from the middle area to the edge area. Visual analysis of the dynamic distribution of water molecules in the pores and the non-homogeneous characterization also demonstrated the good filling effect of RFP on the mortar. Therefore, RFP can be used as an economical and environmentally friendly cement mixing material to replace partial cement and contribute to reducing carbon emissions in the construction industry.

建筑和拆除 (C&D) 废物已造成各种经济、环境和社会问题。本文研究了再生混凝土细粉 (RFP) 作为补充胶凝材料的潜力。从物理特性、力学性能、水化动力学、水化产物、孔隙结构等方面探讨了不同置换水平的RFP对水泥性能的影响及作用机理。在这项研究中，应用了扫描电子显微镜、能量色散 X 射线光谱、X 射线衍射、X 射线荧光、热重分析和等温热量计。结果表明，RFP（小于30%）缩短了凝结时间，提高了水泥的流动性。早期抗压强度比添加 10% RFP的水泥砂浆提高 17.62%。当RFP含量为10%时，混合浆料（175.5 mm）的流动性比纯水泥（162.5 mm）提高了8.0%。随着掺混水泥RFP含量的增加，水化诱导期延长，水化放热峰值速率和蓄热放热量呈明显下降趋势。成核和晶体生长 ( NG) 过程的反应速率远高于界面 (I) 和扩散 (D) 过程。低场核磁共振 (NMR) 技术表明，RFP 填充了砂浆的大孔和中孔。无损分层扫描发现孔隙主要分布在中心区，并具有由中间区向边缘区逐渐减小的梯度分布规律。对孔隙中水分子动态分布的可视化分析和非均匀表征也证明了RFP对砂浆的良好填充效果。因此，RFP可作为一种经济环保的水泥拌和材料替代部分水泥，为建筑行业减少碳排放做出贡献。