Soil mixing is a construction technique that uses augers to mix cement with the existing soil to form a soilcrete mixture that creates a continuous and impervious wall prior to excavation. The soilcrete mix is designed to provide the strength and permeability required for the excavation and allows the site to be excavated under dry conditions, improves the water proofing of the structure being constructed and limits draw down of the water table. When completed, it functions as a water cutoff wall.
Schnabel Foundation Company has a four auger system that forms a continuous wall by drilling a series of primary and secondary strokes. A primary stroke is when all four augers drill into untreated soil; a secondary stroke is when the two outside augers re-drill the outside shafts formed by primary strokes. The sequences start with a primary stroke, then the augers are moved two shaft's widths and another primary stroke is drilled. The augers are moved back and drill a secondary stroke which re-drills the outside shafts of the primary stroke. This creates a jointless concrete face. Then the site is excavated to an elevation where lateral supports are installed.
