Some field sites may have limited workspace and will not allow space for mixing the excavated backfill. An alternative to the soil-bentonite slurry wall in these scenarios is a cement-bentonite slurry wall. Wall construction involves excavation of a trench under a head of slurry composed of water, bentonite, and cement. Instead of backfilling the trench with mixed soil, as in the case of a soil-bentonite wall, the slurry is left to harden and will form a wall with the consistency of a stiff clay.