The term Jet grouting defines the operation of injection in the soil of a cement mixture, through small nozzles, with pressures much higher than conventional ones (up to 600 atm or more) in order to consolidate the foundation soils or to the formation of diaphragms.
The current techniques consist in breaking up the soil by mixing it at the same time with a cementitious suspension, or in removing the finest part by jetting air or water to increase the diffusion of the treatment with a partial replacement effect.
The implementation steps can be summarized as follows:
1) drilling of the ground with a central perforating pipe up to the desired height. the perforation takes place with the circulation of water or, if it is necessary to support the walls of the hole, bentonite mud or similar material;
2) 3) and 4) starting from the bottom upwards extraction of the tube with rotation and simultaneous pressure injection of a cement mixture; in this way the soil breaks up and mixes with the injected product. Proceed until the quota of the campaign plan is reached;
5) joints at the top are repeated operations for adjacent columns of jet grouting, taking care to perform overlaps and interpenetration between the columns (if provided) so as to obtain a single compact final body.