A series of oedometer tests were conducted on slurries with three additives (NaCl, CaCl2, and FeCl3) of different concentrations in pore water (0.1-1.0 mol/L) to investigate the effect of the valency of cations and their concentration on the consolidation-compression behavior of slurries. Further laboratory model tests on the vacuum consolidation of a prefabricated vertical drain (PVD) unit cell were carried out to study the effect of the chemical additives on the performance of the unit cell. Based on the test results, it was found that the compression index and remolded yield stress of the soils increased with the concentration and cationic valence of the additives. For a given void ratio, the value of permeability deduced from the oedometer test results increased with the increase in the concentration and cationic valence of the chemical additives. In addition, the PVD unit cells with cationic chemical additives had a higher rate of consolidation and resulted in higher vacuum pressures in the model ground. Therefore, the chemical additives reduced the degree of apparent clogging induced by non-uniform consolidation of a PVD unit cell and increased the efficiency of vacuum consolidation.
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