Experimental investigation of dredged riverbed sediment treatment via combined electro-osmotic consolidation and cement-fiber solidification

A research graphical abstract showing a sediment treatment process and its analytical results: (1) Materials and Methodology: Wet clay (96% moisture) is treated by combining Electro-Osmotic Consolidation (anode/cathode setup) and Cement-Fiber Solidification. (2) Analysis: Six panels showing the results, including graphs for drainage, moisture content, stress-strain, shear displacement, an XRD pattern, and an SEM image of C-S-H gel-cemented soil. Electro-osmotic consolidation and cement-fiber solidification are widely used for sludge treatment, but their combined effects, especially on dredged riverbed sediment with high initial moisture (>90% dry basis) and clay fraction (>90% by mass, <2 μm), are underexplored. This study used sediment with 96% moisture (dry basis) and over 90% clay-sized particles from the Pearl River, conducting 24 one-dimensional electro-osmosis tests under eight conditions (constant voltage, constant current, and anode advancement), with each condition repeated three times. Results showed that anode advancement reduces interfacial resistance, improves current conduction, and enhances drainage efficiency, resulting in more uniform dewatering. The optimal electro-osmosis condition was then combined with cement, rice husk ash (RHA), and polypropylene fiber for solidification. Mechanical properties were evaluated by unconfined compressive strength (UCS) and direct shear tests. The best curing agent mix was 8% cement, 15% RHA, and 0.3% fiber, with UCS and shear strength increasing with curing age. X-ray diffraction (XRD) and Scanning electron microscopy (SEM) analyses indicated that RHA and cement react to form C-S-H gel, significantly improving soil compactness and strength. The strengthening mechanism involves both physical reinforcement by fibers and chemical stabilization from RHA and cement, enabling efficient treatment and reuse of high-moisture, high-clay sediment.