Influence of salt solutions on the swelling behavior of the compacted GMZ01 bentonite

• Published in: Environmental earth sciences Vol. 74; no. 1; pp. 793 - 802
• Main Authors: Ye, W. M, Zhu, C. M, Chen, Y. G, Chen, B, Cui, Y. J, Wang, J
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-07-2015; Springer
• Subjects: bentonite; Biogeosciences; calcium chloride; deformation; Earth and Environmental Science; Earth Sciences; Engineering Sciences; Environmental Science and Engineering; fluids; Geochemistry; Geology; Hydrology/Water Resources; Mechanics; Mechanics of materials; microstructure; Original Article; sodium chloride; solutions; strains; Terrestrial Pollution; testing; Buffer/backfill materials; Swelling strain; Salt solutions; GMZ01 bentonite; One-dimensional free swelling
• ISSN: 1866-6280; 1866-6299
• DOI: 10.1007/s12665-015-4108-1

During the long-term operation of a deep geological repository, infiltration of pore fluids with different chemical compositions can influence the swelling behavior of the compacted bentonite. In this paper, using a self-developed swelling deformation apparatus, one-dimensional free swelling tests were conducted on densely compacted GMZ01 bentonite specimen with an initial dry density of 1.70 g/cm³, with infiltration of de-ionized water, NaCl, or CaCl₂ solutions at different concentrations. Results show that the swelling strains of GMZ01 bentonite specimens infiltrated with salt solutions were significantly lower than that of those infiltrated with de-ionized water. In fact, the swelling strain decreased in a form of power function with the increasing concentration of infiltration solutions. For a given concentration, the one-dimensional swelling strain of specimens contacted with NaCl solutions was higher than that of the specimens infiltrated with CaCl₂ solutions. However, the difference of the swelling strains decreased with increasing concentrations. This phenomenon could be explained by the impact of cation types on the microstructure of bentonite.