Experimental study on electroosmosis-solidification of engineering slurry pretreated by composite flocculant

During the construction of pile foundations, the generation of vast amounts of engineering slurry, with poor geotechnical mechanical properties, requires expeditious treatment. In this paper, composite flocculants, consisting of anionic polyacrylamide (APAM), slaked lime (Ca (OH)2), and poly aluminum chloride (PAC) in varying proportions, were used to pretreat high water content (150%) engineering slurries. Afterwards, electroosmosissolidification treatment tests were carried out on the pretreated slurries to determine the influence of composite flocculant pretreatment on the efficacy of electro-osmosis treatment. The results indicate that the addition of a composite flocculant, APAM-PAC-Ca (OH)2, allows for the formation of flocs with structural pores within the slurry, which creates more favorable conditions for electroosmotic drainage treatment. After electroosmosis, the composite flocculant treated slurry led to lower average corrosion coefficients and presented with more uniform changes to soil moisture and 50% higher undrained soil shear strengths compared to samples treated with a single flocculant. The incorporation of Ca (OH)2 in the composite flocculant was shown to effectively decrease the extent of anode corrosion. Additionally, scanning electron microscope (SEM) imaging of the composite flocculant-treated and electroosmosis-treated slurries show the presence of CSH, CAH, AFt, polymer network structures and other products in the solidified slurry. The filling of the pores demonstrated the strengthening of the soil, meeting the requirements of external transportation and reuse.