Pore Space Geometry (PSG) - Aims & Experimental Concept

  • To study the changes of rock structural properties during sampling by comparing porosities in samples whose pore space was preserved by in-situ resin impregnation experiment results with those which were drilled and taken to the laboratory before resin impregnation.

  • To study rock porosity and morphology of pore space in intact rock matrix (i.e. tortuosity and constrictivity, the connected porosity and accessible pore space).

  • To use spatial porosity distribution provided by the 14C-PMMA method for the new development of modelling tools of the heterogeneous matrix diffusion.

Experimental Concept

The experiment is based on the previously developed 14C-PMMA method which consists the following steps during impregnation in the laboratory:

  • Drying of centimetre scale rock samples under vacuum
  • Impregnation with 14C-PMMA under vacuum
  • Radiation induced polymerisation using a 60Co source
  • Detection of 14C-PMMA in the rocks with autoradiography
  • Digital image analysis of beta autoradiographs (*) to provide spatial porosity distribution of the rocks

The following steps were performed during the in-situ experiment at the GTS:

  • Drying of the intact rock by air ventilation
  • Injection of 14C-PMMA into the rock matrix
  • Polymerisation of 14C-PMMA by heating
  • Overcoring of the resin impregnated matrix
  • Detection of the 14C-PMMA in the granite matrix using beta autoradiography techniques (*)

(*) The location of the 14C-PMMA on the rock samples can be determined by placing a thin, plastic film over the rock sample. The beta particles from the 14C-PMMA in the rock matrix interact with the film and leave a unique signal. The films are analysed in an instrument that converts the area where beta particles interacted with the film into an optical density in a technique called beta autoradiography. The images produced are called beta autoradiographs.


Pore Space Geometry (PSG) Experiment

The GTS underground facilities are also available to interested 3rd parties for underground testing and research. The GTS offers cost-effective access to a fully developed, well characterised underground research facility with round the year logistical support - please contact Dr. Ingo Blechschmidt, Head of the Grimsel Test Site, for further details.
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