Basic problems and low-carbon technical path of construction spoil recycling
Jianzhuang Xiao, Jianyu Shen, Zhenhua Duan, Yongxiang Zhou, Fumin Ren, Xu Xiao
Abstract
<p indent="0mm">In the past <sc>20 years,</sc> China has made tremendous progress in urbanization and infrastructure construction, but it has also generated a large amount of construction spoil that is difficult to handle. The annual emission of construction spoil in China is huge, but its high value-added resource utilization rate is very low. Currently, it is still mainly landfilling and stacking to construction spoil storage sites, and the current disposal process generates a large amount of carbon emissions. In view of the national strategy of carbon peak and carbon neutral, as well as the current situation of low resource utilization rate of construction spoil, the basic problems at the technical level are explored and the feasible and innovative technical path was put forward. Firstly, the definition, composition and harmfulness of construction spoil are expounded. The existing disposal and recycling technologies of construction spoil are divided into four types, including direct reuse, simple treatment and conditioning, solidification and sintering. The development context and regional differences of four types of disposal and recycling technologies of construction spoil in China in the past <sc>20 years</sc> are combed, the main research and application directions of those technologies are analyzed, and the technical terms are clarified and defined, and the shortcomings of previous relevant research are pointed out. The basic properties of construction spoil are intensively introduced and the scientific principles of four types of disposal and recycling technologies including direct reuse, simple treatment and conditioning, solidification, and sintering, are further revealed. And we suggested that low-carbon solidification technology and carbon-reduction sintering technology are the future development trends. Based on the case study of the Pinglu Canal, it is found that the current situation of disposal of construction spoil in China is still relatively preliminary. According to the current situation, the basic problems of low utilization rate of construction spoil at the technical level are analyzed, mainly including insufficient space, insufficient analysis of demand, high disposal costs, and insufficient attention to environmental impacts of the disposal of construction spoil. Then the potential of carbon absorption and sequestration of construction spoil itself and the possibility of reducing carbon emissions in the process of resource utilization and disposal of construction spoil is analyzed. Finally, to address these basic problems and in combination with China’s dual-carbon strategy, innovative solutions and high-value-added strategies such as recycling at multi-scenario through multi-path, co-processing, and digital technology empowerment are proposed, new potential technologies with low-carbon and carbon sequestration such as raw earth construction and 3D printed soil are suggested, and new technology paths for comprehensive utilization of construction spoil including low-carbon solidification, carbon reduction sintering, and other technologies are put forward. With the continuous development of the domestic construction industry, the recycling of construction spoil will provide a new direction for saving natural resources, alleviating urban environmental pressure, and achieving green construction.