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> PSG Project
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Pore Space Geometry
(PSG)
Aims |
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- 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.
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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.
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