Jet grouting is the high pressure injection of a cementicious grout slurry into a soil strata that hydraulically mixes the in situ material with grout. The resulting amended soil material is called soil-crete. The most common technique used in jet grouting involves the insertion of the jet grout pipe to the design depth of the soil-crete column bottom. The pipe is typically a high pressure version of specialized drill rods with a hollow center and special jet grouting nozzles at the tip.
Next, the jetting pipe is rotated slowly and pressurized with a grout slurry made typically of Portland cement and water. The high pressure (4000 – 6000 psi) forces the grout out laterally through special ports located in the sides of the pipe, near the bottom. The slurry exits the jet port at a very high velocity, impinging on the soil and penetrating it from several inches to feet away from the jets.
The rotating jets destroy soft soil formations, and intimately and uniformly mix the native soil with cement. Finally, the rotating pipe is drawn slowly upward at a carefully controlled rate so that the jets create a nearly cylindrical column of treated soil. The actual diameter of the soil-crete column is dependent on specific items; soil conditions, grout mix, nozzle diameter, rotation speed, withdrawal rate and grout pressure.
Jet grouting "recipes" are tailored to each project based upon the soil type and the application. Jet grouted columns may be interconnected to form cut off walls or structural sections.
Wet Soil Mixing
Wet soil mixing is the mechanical mixing of in situ soil with cement grout slurry using a hollow stem paddle type mixer. The method relies on the introduction of engineered grout slurry to create soil-cement (soil-crete) elements for soil stabilization, or to support earth or building loads.
The aim is to achieve improved engineering properties, generally compressive strength, shear strength or permeability. Wet soil mixing can also be used to form ground water barriers, immobilize and or stabilize contaminants or as a chemical treatment system.
Typical applications include improvement of bearing capacity in soft or loose soils for light industrial structures or embankments, retaining walls, groundwater barriers and more.