Luo Jing, Huang Rong, Wang Junjie, Zhang Yi
Department of Civil Engineering, Tsinghua University, Beijing 100084, China.
Materials (Basel). 2024 Oct 14;17(20):5020. doi: 10.3390/ma17205020.
As the world's largest producer of construction waste, China's recycling and related policies are of the biggest concern to the world. However, the effective disposal and reuse of this waste has become an important issue since currently China still has a very low recycling ratio compared to developed countries, and most of the waste concrete was only simply broken and used as low-grade recycled aggregates for subgrade cushion, cement stabilized crushed stone, and filler wall. In this paper, a concrete cycle model focusing on how to effectively recycle and utilize waste concrete is put forward to prepare high quality recycled concrete, especially through a series of technical means, such as effective separation, carbon sequestration, and reactivation. Producing high quality recycled concrete can not only replace traditional concrete but also effectively reduce the consumption and waste of raw materials. What's more, the calculation results show a potential of significantly carbon sink; for every ton of recycled cement produced, the CO emission could be reduced by 0.35-0.77 tons compared to ordinary Portland cement, corresponding to a reduction of 47%-94%; and for every ton of recycled concrete produced, the CO emission could be reduced by 0.186 tons compared to normal concrete. A yearly CO sequestration of 1.4-3.08 gigatonnes could happen if the ordinary Portland cement could be replaced by the recycled cement around the world. Taking the currently accumulated construction and demolition (C&D) wastes globally, the production of recycled cement, recycled aggregates, and recycled concrete could induce a significant carbon sink in the world.
作为世界上最大的建筑垃圾生产国，中国的回收利用及相关政策备受世界关注。然而，由于目前中国的回收率与发达国家相比仍非常低，且大部分废弃混凝土仅被简单破碎并用作路基垫层、水泥稳定碎石和填充墙的低等级再生骨料，这种废弃物的有效处置和再利用已成为一个重要问题。本文提出了一个专注于如何有效回收和利用废弃混凝土以制备高质量再生混凝土的混凝土循环模型，特别是通过一系列技术手段，如有效分离、碳封存和再活化。生产高质量再生混凝土不仅可以替代传统混凝土，还能有效减少原材料的消耗和浪费。此外，计算结果显示出显著的碳汇潜力；与普通硅酸盐水泥相比，每生产一吨再生水泥，二氧化碳排放量可减少0.35 - 0.77吨，相当于减少47% - 94%；与普通混凝土相比，每生产一吨再生混凝土，二氧化碳排放量可减少0.186吨。如果全球范围内普通硅酸盐水泥能被再生水泥替代，每年可实现1.4 - 3.08吉吨的碳封存。以目前全球累计的建筑拆除废弃物来看，再生水泥、再生骨料和再生混凝土的生产可在全球范围内形成显著的碳汇。
