Effect of fly ash addition on slurry dewatering by electro-osmosis combined with mechanical pressure

In this study, fly ash was used as an additive to increase the dewatering efficiency of an excavated soil slurry treated by electro-osmosis combined with mechanical pressure and thus effectively obtain a low-moisture treated slurry with wider applicability; the properties of the treated slurry were also studied. The results showed that, at a fly ash dosage of 5%, the drainage volume was 350 mL, which presented significantly better dewaterability properties than the unconditioned slurry, the water content of the anode and cathode layer after treated was 20.5% and 19.1%, the compressibility coefficient was 0.170 MPa(-1)and 0.152 MPa-1, and the shear strength was 81.2 kPa and 85.1 kPa, respectively. And we also studied the physical properties of the treated slurry at different locations, the physical properties were also affected by the fly ash dosage. It was concluded that fly ash used in adequate concentrations can reduce the slurry water content, and fly ash also can improve the mechanical properties of excavated soil slurry after the mechanical dewatering combined with electro-osmosis.