a series of one-dimensional compression tests was conducted to examine and compare the hydro-mechanical behaviour of light backfill (lbf) material, composed of 50% bentonite and 50% sand, in the presence of distilled water and 100 g/l cacl2 and 200 g/l cacl2 solutions. in addition, the hydro-mechanical parameters of lbf required for compliance modelling of the deep geologic repository (dgr) emplacement room sealing system were determined. the tests were conducted on 50-mm-diameter by 10-mm-thick lbf samples, using standard lever arm consolidation equipment. several different loading and wetting paths were examined, including allowing the lbf to swell up to 20% vertical strain on distilled water or solution uptake and constraining the lbf from swelling on distilled water or solution uptake.