Jet grouting is a general term for a variety of techniques employing one, two or three fluids to mix in-situ or replace soil underground with cement based grout mix.
The common denominator of these methods is the use of very high pressure in the injected fluid, which mixes or displaces the soil, rather then permeating it as in conventional grouting techniques. The possibility of creating treated horizons or columns of improved soil results in a variety of applications ranging from vertical cut-offs to bottom plugs, from underpinning to underground strutting elements.
Depending on the number of the fluids used, the European standards EN 12716 has identified three main techniques:
• SINGLE FLUID, a water/cement mixture is injected to break up and simultaneously mix the soil in-situ.
Diameters usually range from 1.31 ft. to 3.28 ft.
• DOUBLE FLUID, a combination of air and water/cement mix is injected to break up and simultaneously mix the soil in-situ.
Diameters usually range from 2.62 ft. to 8.20 ft.
• TRIPLE FLUID, a combination of water/air jet is used to break up and partially remove the soil in-situ, whereas soil mixing is ensured by a lower water/cement injection.