Jet grouting uses a high-pressure jet of fluid to break up and loosen the soils at depth and mix them with a cementitious grout to form columns, panels or entire blocks of improved material in the ground. The result is an improvement in the soils mechanical and permeability properties.
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.
Variations in method:
Soil loosening and grout injection are performed by a jet of high pressure grout from nozzles at the bottom end of a drill rod.
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. Mainly used for panel walls, underpinning of structures and sealing slabs.
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 is mainly used for the treatment of cohesive soils and in loose or soft-rock soils to reinforce them or, in certain cases, to make them impermeable.