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Engineered Backfill

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It is currently proposed that underground tunnels and access shafts within nuclear waste repositories will be backfilled with a mixture of host rock and bentonite. Bentonite is a highly swelling clay and once hydrated will ensure low hydraulic conductivities throughout the backfill material. However difficulties associated with localised hydration have been reported, along with poor contact with the host rock. Furthermore bentonite is costly. This research aims to engineer microbial carbonate precipitation within the backfill material to reduce permeability, improve the hydration of the backfill material and contact with the tunnel boundary while also reducing costs. The hydro-mechanical properties of a range of different backfill materials subjected to biomineralisation treatment will be investigated using both macroscopic tests and microscopic studies.

Rowe cell used for measuring permeability of biomineralised backfill mixtures

Last Updated on Monday, 18 July 2011 14:21