A low-carbon approach to recycling engineering muck to produce non-sintering lightweight aggregates: Physical properties, microstructure, reaction mechanism, and life cycle assessment. (20th January 2023)

• Record Type: Journal Article
• Authors: Gao, Wenbin; Zhang, Hongen; Ren, Qiang; Zhong, Yijin; Jiang, Zhengwu
• Is Part Of: Journal of cleaner production. Volume 385(2023)
• Publication Date: 2023-01-20
• Subjects: Engineering muck -- Low-carbon approach -- Lightweight aggregates -- Reaction mechanism -- Life cycle assessment; Factory and trade waste -- Management -- Periodicals; Manufactures -- Environmental aspects -- Periodicals; Déchets industriels -- Gestion -- Périodiques; Usines -- Aspect de l'environnement -- Périodiques; 628.5
• DOI: 10.1016/j.jclepro.2022.135650
• Languages: English
• ISSNs: 0959-6526

Abstract

Abstract: Engineering muck represents a typical, large output construction waste. However, the comprehensive utilisation rate of engineering muck is typically low. Large quantities of engineering muck accumulate in the open air, exerting a pressure on scarce land resources and exacerbating the risk of landslides. There is an urgent need for the efficient waste management techniques to improve the long-term utilisation of engineering muck. In this study, a low-carbon, low-cost, and innovative approach to recycling engineering muck to produce non-sintering lightweight aggregates (NSLWA) is reported. NSLWA was successfully prepared by a bonding granulation technique, and a systematic investigation on the physico-mechanical properties, microstructure, and corresponding reaction mechanism of NSLWA was conducted. The experimental results indicated that the prepared NSLWA, possessing a loose bulk density of 0.91–1.16 g/cm 3 and a cylinder strength of 1.22–11.7 MPa, met the performance requirements of lightweight aggregates (GB/T17431.1 2010). The mechanistic analysis demonstrated that the cylinder strength of NSLWA could mainly be attributed to two factors: 1) the cementation effect of hydration products and 2) cohesive forces between clay particles. Finally, the environmental impact was analysed by life cycle assessment. The global warming potential (GWP) was in the range of 47.4–201.2 kg CO2 -eq/t NSLWA; Processing NSLWA by engineering muck could enable a reduction of GWP by 31–84% relative to that a landfill disposal process following chemical stabilisation. Compared with the lightweight aggregates obtained after sintering processes, the GWP of NSLWA was reduced by 11.7–79.2%. The total costs of NSLWA processing were in the range of 8.1–20.9 $/t NSLWA, bringing about an economic benefit of 9.0–21.8 $/t NSLWA compared with the traditional artificial aggregates. The findings of this work will guide the eco-friendly and economical management of engineering muck to support the sustainable development of the aggregate manufacturing industry. Graphical abstract: Image 1 Highlights: A low-carbon and low-cost approach to engineering muck management. Qualified lightweight aggregates are produced from engineering muck. The CO2 -eq emissions can be reduced by 31–84%. Yielding economic benefits of 9.0–21.8 $/t.