(GRS-302) Self-Sealing Barriers of Sand/Bentonite-Mixtures in a Clay Repository

Several years ago, GRS performed laboratory investigations on the suitability of clay/mineral mixtures as optimized sealing materials in underground repositories for radioactive wastes /JOC 00/ /MIE 03/.
 
The investigations yielded promising results so that plans were developed for testing the sealing properties of those materials under representative in-situ conditions in the Mont Terri Rock Laboratory (MTRL). The project was proposed to the "Projektträger Wassertechnologie und Entsorgung (PtWT+E)", and finally launched in January 2003 under the name SB-project ("Self-sealing Barriers of Clay/Mineral Mixtures in a Clay Repository").
 
The project was divided in two parts, a pre-project running from January 2003 until June 2004 under contract No. 02E9713 /ROT 04/ and the main project running from January 2004 until June2012 under contract No. 02E9894 with originally PtWT+E, later renamed as PTKA-WTE.
 
In the course of the pre-project it was decided to incorporate the SB main project as a cost shared action of PtWT+E and the European Commission (contract No. FI6W-CT-2004-508851) into the EC Integrated Project ESDRED (Engineering Studies and Demonstrations of Repository Designs) performed by 11 European project partners within the 6th European framework programme. The ESDRED project was terminated prior to the termination of the SB project. Interim results were reported by mid 2009 in two ESDRED reports /DEB09/ /SEI 09/.
 
This report presents the results achieved in the whole SB-project comprising preceding laboratory investigations for the final selection of suited material mixtures, the conduction of mock-up tests in the geotechnical laboratory of GRS in Braunschweig and the execution of in-situ experiments at the MTRL.