Permeability change of crystalline silicate mineral-packed bed column by highly alkaline plume

Hideo Usui, Yuichi Niibori, Osamu Tochiyama, Hitoshi Mimura

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

For the construction of the geological disposal system, the use of the cementitious material may change the permeability of the natural barrier around the repository. Cementitious materials may alter the pH of ground water to highly alkaline. Also, the potential permeability change of the natural barrier is one of the notable factors for performance assessments of geological disposal systems. In the high pH region, the solubility of silica is very high compared to that in the natural pH (around 8). Therefore, highly alkaline groundwater would dissolve and alter a part of rock surface. Usui et al. (2005) reported that the change of mineral pore structure due to chemical reaction is the key factor to consider the change of the permeability [5-6]. Moreover, such a change of the pore structure was considered to be the result of the spatial heterogeneity of chemical composition. Since such spatial heterogeneity exists also in the sedimentary rocks consisting of crystalline minerals such as quartz and feldspar, we need to examine natural rock, in order to obtain more reliable understanding about the change of permeability induced by highly alkaline groundwater (plume). In this study, silica sand as crystalline mineral was packed in the column, and the effect of dissolution induced by the highly alkaline plume on the permeability-change was examined. The silica sand particles mainly consist of SiO2 and include Al2O 3, FeO, and K2O. The volumetric flow rate and the pressure difference between the inlet and outlet of the column were measured, and the permeability was calculated. At the same time, the concentrations of elements in the fluid were measured by ICP-AES. The experimental result showed that permeability decreased gradually, although the silica sand was continuously dissolved in the column. The behavior of the permeability is considered to be the result from the rearrangement of the particles, or precipitation of secondary mineral. In the column test using the silica sand as packed mineral, the flow-path seems to be clogged by the rearrangement of the particles rather than the increase of the pore space between the particles.

Original languageEnglish
Title of host publicationScientific Basis for Nuclear Waste Management XXX
Pages581-586
Number of pages6
Volume985
Publication statusPublished - 2007 Dec 1
Event2006 MRS Fall Meeting - Boston, MA, United States
Duration: 2006 Nov 272006 Nov 29

Other

Other2006 MRS Fall Meeting
CountryUnited States
CityBoston, MA
Period06/11/2706/11/29

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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  • Cite this

    Usui, H., Niibori, Y., Tochiyama, O., & Mimura, H. (2007). Permeability change of crystalline silicate mineral-packed bed column by highly alkaline plume. In Scientific Basis for Nuclear Waste Management XXX (Vol. 985, pp. 581-586)