Abstract: In order to study the influence of zinc ions on the compressibility of remolded bentonite, a series of tests including one-dimensional compression, free swelling ratio, physicochemical property, and scanning electron microscopy were performed on artificially prepared bentonite of high water content with different concentrations of zinc ions. Test results indicate that, when the vertical load is lower than a critical value of 200 kPa, the void ratio and compression index of the contaminated bentonite will decrease with the increasing concentration of zinc ions under a constant vertical load. However, if the concentration of zinc ions is greater than a threshold value of 0.02 mol/L, there will be little change in void ratio of bentonite; and the compression index will just decrease a little. As the vertical load is greater than 200 kPa, basically the void ratio of bentonite will not be influenced by the physicochemical property of the pore fluid but only be determined by vertical load. In addition, experimental analysis shows that as the concentration of the zinc ions increases, pH value of the pore fluid and specific surface area will be decreased; but the particle diameter will be increased. Furthermore, the dispersed structure of bentonite will be gradually destroyed; clay mineral flakes will form big aggregates; and large inter-aggregate voids will come into being due to the zinc contamination.

Key words: zinc ions, bentonite, compressibility, physico-chemical effect, microstructure