Evolution of swelling properties of a compacted hectorite soaked by nickel solutions.
type: Distribution
access URL: https://insu.hal.science/hal-00089150
format: HTML
issued: 2026-05-08T17:23:12.009980
modified: 2026-05-08T17:23:12.000052

Evolution of swelling properties of a compacted hectorite soaked by nickel solutions.
type: Dataset
contact point: Organization
  fn: CCSD
keyword: infoeu-reposemanticsconferenceobject
keyword: conference-papers
keyword: sdustumisciences-of-the-universe-physicsearth-sciencesmineralogy
landing page: Joint meeting of the Clay Minerals Society and the French Clay Group" - 43rd Annual Meeting of the CMS - 4ème Colloque du GFA
description: Nowadays, subsurface waste disposal is based on the concept of compacted clay barriers, characterized by a low permeability and high cation retention. The aim of this experimental study is not only to reproduce at the laboratory scale the in-situ compaction of saturated clays, but also to focus on the evolution of the clay properties. Therefore, percolation experiments have been performed using an oedometer cell equipped with an injection system under constant pressure [1]. The chosen clay is the hectorite from Hector (California, USA), with the structural formula (Na0.25Ca0.04)(Mg2.74Li0.31)Si3.97O10(OH,F)2.nH2O. This hectorite is associated with minor calcite. For all experiments, the hectorite sample was compacted at 0.5 MPa, and then soaked at 0.3 MPa with deionised water or Ni(NO3)2 0.01 M solution. Moreover, Ni(NO3)2 solutions were injected in clays for two different initial water saturation degrees: Sr=0.3 (dry clay) and Sr=1 (water-saturated). Some mechanical unloadings were also performed along the experiments, in order to test the swelling behaviour of the clay at different exchange rates. Axial strain variations were monitored during testing. Moreover, output solutions from the oedometer, i.e. leachates, have been regularly analysed for Ni2+, Na+, K+, Ca2+, Mg2+ and Li+. These analyses allowed to calculate the exchange ratio, KNa+, defined as the fraction of Na+ released to the solution, compared to the bulk Na+ content in the starting clay, in atomic proportion. Two samples, run in the oedometer with Ni(NO3)2 solution, were also obtained, with an exchange ratio KNa+ of 0.19 for Sr=0.3 and 0.34 for Sr=1. Whatever the initial saturation degree, neither Ni2+ nor Li+ have been detected in the leachates, and the Na+ content in the solutions is around 100 times higher than Ca2+, Mg2+ and K+: Ni2+ has been totally fixed by hectorite and exchanged to Na+. Hydraulic conductivity, k, was calculated from the Darcy law, using the expression elaborated for a saturate…
issued: 2026-05-08T17:23:12.005115
language: en
modified: 2026-05-08T17:23:12.005119

test_moissonnage_selune
type: Agent