Jet Grouting

Jet grouting is a construction process that uses a high-pressure jet of fluid (generally 20 – 40 MPa) to break up and loosen the soil at depth in a borehole and to mix it with a self-hardening grout to form columns, panels and other structures in the ground.

The parameters for the jet-grouting process and the desired final strength of the treated soil depend on a number of characteristics, such as the soil type, the technique used and the objective to be reached. In granular soils, the high-pressure jet breaks up the grains through erosion, while in a cohesive soil, such as clay, the jet breaks the mass up into small particles. High pressure is needed to produce the kinetic energy required for the jet through a small-diameter nozzle. Waste material from the process (a mix of soil, water and binder) is recovered at the surface before being taken away for disposal.

Three basic jet grouting systems are currently used:

SINGLE JET
Soil loosening and grout injection are performed by a jet of high pressure grout from nozzles at the bottom end of a drill rod.

TWIN JET
Soil loosening and grout injection are performed by a high pressure jet of grout shrouded by a concentric jet of air which increases the radius of action.

TRIPLE JET
Soil loosening is performed by a jet of water shrouded by concentric jet of air. Grout injection is performed by a separate jet of grout.

The process can be used in all loose or soft-rock soils to reinforce them or, in certain cases, to make them impermeable: underpinning buildings, dam cut-off wall, excavation retaining wall, pipe roofing for tunnels, with possible reinforcement of side-walls, etc.

When jet grouting is used for soil impermeability, it is sometimes necessary to use an additional grouting treatment, depending on the required final soil properties.

Download the Jet Grouting Brochure: