The objective of this study is to experimentally determine the mechanical and hydraulic performance of consolidated crushed salt as affected by applied stresses and consolidation period. The crushed salt has grain sizes ranging from 0.075 to 4.76 mm. The constant axial stresses are applied to the crushed salt samples installed in steel cylinders, varying from 2.5, 5, 7.5to 10 MPa. The nitrogen gas flow testing is performed to determine intrinsic permeability of crushed salt during consolidation up to 90 days. Higher axial stresses applied result in higher consolidation magnitude and density. The axial stresses and consolidation period exponentially decrease the void ratio and intrinsic permeability of the crushed salt. The uniaxial compressive strengths are measured after the samples have been consolidated for 3, 5, 7, 10, 15, 30, 90 days. The applied axial stresses and consolidation time increase the compressive strength and elastic modulus and decreases the Poisson's ratio.

1. Introduction

The function of the crushed salt backfill is to act as a geotechnical long-term barrier against inflowing brine or water. Crushed salt has been widely recognized as the most suitable backfill material (Heemann et al., 1999; Case and Kelsall, 1987). Crushed salt can be compacted and its initial porosity and permeability will decrease. Over long periods, the crushed salt is expected to gradually reconsolidate into a material comparable to intact rock salt (Heemann et al., 1999). For crushed salt emplaced in an opening in a rock salt formation, the consolidation is driven by the creep closure of the adjacent rock. The primary advantages of crushed salt are availability, low cost and obvious compatibility with host rock (Stormont and Finley, 1996).

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