The characteristics of high moisture content, poor compaction, and excessive heavy metal content hinder the reuse of dredged sediment in engineering practice [1]. Meanwhile with the advancement of industrialization, there are still challenges of industrial solid waste large stockpiles and low comprehensive utilization rate in various countries [2]. To collaboratively address these issues, a new low-carbon solid waste-based cementitious material was developed in this study, primarily composed of various industrial solid wastes, including phosphogypsum, slag, and fly ash, for solidifying dredged sediment. The mix proportions of solid waste-based cementitious material were optimized through response surface methodology. Additionally, the mechanical properties, environmental stability, and sulfate corrosion durability of solidified dredged sediment were systematically investigated. The results indicate that the 28d-unconfined compressive strength (UCS) of the optimal solid waste-based cementitious material (PBC) reached 24.65 MPa. Compared with ordinary Portland cement (OPC), the costs and carbon emissions of PBC preparation reduced by 54.86% and 96.84%, respectively. Furthermore, the mechanical and environmental performances of the solidified sediment was comprehensively optimized under the following conditions: 20% binder dosage, 75% moisture content, and an OPC:PBC ratio of 3:7. The new low-carbon binder solidified dredged sediment effectively immobilized fluorine, phosphate, sulfate ion and multiple mental ions, reducing their leaching concentrations, and making them below the limits specified in relevant environmental standards. After 60 days of exposure to a sodium sulfate environment, samples solidified under optimal conditions exhibited no cracking and maintained stable compressive strength. In this presentation, the OPC and PBC composite binder solidified sediment provided a technically feasible and environmentally sustainable approach for the reuse of high moisture content soils in engineering applications.

References:

[1] L. Wang, J.S.H. Kwok, D.C.W. Tsang, C.S. Poon. J. Hazard. Mater. 2014, 283, 623-632.

[2] J. Wu, Y.F. Deng, G.P. Zhang, A.N. Zhou et al. J. Clean. Prod. 2021, 321, 128920.