The generation of bentonite colloids has been investigated by means of column experiments with bentonite compacted at the engineering barrier density and using water flows as low as 0.04 ml/h (≈350 ml/year). Results on generation of bentonite colloids in these “all-bentonite” columns suggested that most of the colloidal material observed in the eluted water is due to erosion of the plug. Therefore new column experiments in which granite and compacted bentonite are in contact have been designed and the effects of the water flow analysed. The physico - chemical characteristics of the colloidal material obtained in the “all-bentonite” and “bentonite plus granite” column experiments have been compared as well as its stability. Results show that bentonite colloids that have been in contact with granite always present a higher negative charge, this indicating that they could be stable in the natural environment.
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Missana, T., Turrero, M.J. & Melon, A. Generation and Characterisation of Colloids of the Near Field / Far Field Interface. MRS Online Proceedings Library 556, 647 (1998). https://doi.org/10.1557/PROC-556-647