Separation is a fundamental step for concrete recycling, enabling not only the achievement of reliable and cleaner recycled aggregates but also the better re-use of the remaining concrete constituents. Recently, a new hydraulic binder produced from the hydrated cement paste contained in waste concrete, which is associated with lower processing temperatures and carbon dioxide emissions, has gained momentum in the history of concrete recycling. However, a decisive turning point for its application lies in the successful individualisation of the cement paste and aggregate initially contained in concrete debris. This paper describes a new patented method involving a mechanical comminution stage and a high-intensity magnetic separation process to obtain the cementitious fraction in concrete and retrieve cleaner fine aggregate. The efficiency of the proposed method was assessed through image analysis, thermogravimetry, X-ray diffraction and acid attack. In addition, cement pastes produced with the obtained recycled cement after thermal activation were characterised in terms of mechanical strength. Findings suggest that the proposed method effectively separated the main concrete constituents, especially when the waste material was reduced to the size range 150–500 μm. It was possible to obtain a recycled binder at the current laboratory scale with up to about 80% cement content by weight (nearly 90% in volume). Furthermore, a cleaner recycled fine aggregate, with minimal cement paste contamination, as low as less than 3 wt%, was also obtained. The mechanical strength of pastes with recycled cement retrieved from waste concrete was about 70% of that of reference pastes of equal water/binder produced with recycled cement from non-contaminated waste cement pastes.

分离是混凝土回收利用的基本步骤，不仅可以实现可靠，清洁的回收骨料，而且可以更好地重复利用剩余的混凝土成分。最近，废混凝土中所含的水合水泥浆生产出一种新型的水硬性粘结剂，它具有较低的加工温度和二氧化碳排放量，在混凝土回收的历史上已获得发展动力。但是，其应用的决定性转折点在于成功地将最初包含在混凝土碎屑中的水泥浆和骨料个性化。本文介绍了一种新的专利方法，该方法涉及机械粉碎阶段和高强度磁选过程，以获得混凝土中的胶结部分并回收更清洁的细骨料。通过图像分析，热重分析，X射线衍射和酸侵蚀评估了所提出方法的效率。另外，以机械强度表征了用热活化后所得的再生水泥制得的水泥浆。研究结果表明，所提出的方法可以有效地分离出混凝土的主要成分，尤其是当废料减少至150-500μm的尺寸范围时。在目前的实验室规模下，有可能获得一种再生的粘结剂，其水泥含量约为80％（重量）（体积约为90％）。此外，还获得了清洁的再循环细骨料，其具有最小的水泥浆污染，低至小于3重量％。