Effect of Suction Changes on the Microstructure of Compacted Crushed Argillites under Constant-Volume Conditions

Crushed and compacted argillite extracted from Bure site (France) has been proposed as a possible sealing and backfilling material in the geological high-level radioactive waste disposal. In order to better understand its coupled hydro-mechanical behaviour in the real storage situation, changes in microstructure of two crushed argillites of different grain size distributions with decreasing suction under confined condition were investigated using mercury intrusion porosimetry (MIP). The results show that wetting under constant-volume condition reduces the size of macro-pores, without significantly affecting the micro-pores size. A clear effect of grain size distribution on the microstructure was also observed: two pore families were identified for the coarse soil; however, there was only one maro-pore family for fine soil (inter-aggregates pores).