Spanish research activities in the field of backfilling and sealing. A preliminary study of some spanish sedimentary (Madrid Basin) and hydrothermal (Almeria) bentonites

The purpose of the research in progress is to demonstrate the adequacy of spanish bentonites as engineered barriers according to the spanish High Level Radioactive Waste (HLW) disposal concept. The methodology of the project and some preliminary results are presented. Three clay deposits in the Madrid Basin and three clay deposits in the Almeria area are being studied. The saponites from Cerro del Aguila (Madrid) with a very high content in MgO (13-28%) and a liquid limit between 130-240 seem to be the most promising bentonites from the Madrid area. The bentonites of Serrata de Nijar (Almeria) with a smectite content above 80%, high specific surface and high cation exchange capacity have been selected as the candidate materials from the Almeria zone