Thermo-hydro-mechanical tests using vapor and liquid transfer on a clay-based mixture

Within the framework of the OPHELIE surface mock-up test -a Belgian reference repository concept for high level radioactive waste disposal (Verstricht et al. 2002)- an exhaustive experimental program under oedometer conditions was carried out to characterize the thermo-hydro-mechanical response of the backfill material used. This material, precompacted in high-density blocks, is made up of 60% FoCa clay, 35% sand and 5% graphite (dry mass basis). This paper focuses on the description of the temperature and suction controlled oedometer equipment and the experimental techniques used. Selected experimental results related to water retention properties, compressibility on loading at different total suctions and temperatures, as well as swelling capacity on soaking and heating, are also presented and interpreted.