Soil-Cement-Bentonite (S-C-B) cutoff walls are a more recent development in slurry trenching methodology. S-C-B cutoff walls combine low permeability with moderate strength. This technique is economical on sites where the trench soil may be reused in the backfill minimizing disposal. S-C-B cutoff walls are constructed the same way as S-B cutoff walls except that cement is added to the backfill mixture resulting in an impermeable mixture with moderate strength.
Typical permeability is in the 10-6 cm/sec to 10-7 range. S-C-B backfill usually have an unconfined compressive strength (UCS) between 25 to in excess of 300 psi. The presence of cement creates strength, but also challenges. The potential for cold joints is greater with this technique; therefore quality control measures must be more exacting.