Chemical flocculants or coagulants for dewatering dredged slurries

4 Chemical flocculants (or coagulants) for dewatering dredged slurries 

To minimize the adverse effects of this filter cake, chemicals are added to the dredged slurry during pumping. One group consists of standard chemicals (eg, hme, alum, and ferric chloride) and a second group consists of synthetic polyelectrolytes (eg, polyacrylamide, acrylamide copolymers). The effectiveness of these additives is readily seen in Fig. 21.5. 

To quantify the effect of adding a flocculant to a slurry of inorganic sUty clay soil (in this case a clay of low plasticity with a CL-designation), the pillow test method was 

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