Soil mixing

What is it?

Soil mixing improves the characteristics of soil in situ by mixing it with a grout, usually cement slurry. This technique requires no prior transformation of materials: the soil in situ is not extracted and is used as it is. Since it uses the soil in situ, soil mixing involves little excavation and therefore little earth has to be moved and less machinery is needed. Since it also requires less grout than other soil reinforcement techniques, soil mixing is environmental friendly.

Soil mixing
Tool for implementing the wet method

Soil mixing
Tool for implementing the dry method


Soil mixing is done in three stages:

• destructurating the soil in situ,
• injecting the grout,
• mixing.
The dry method is used for soils with high water content: a tool injects the grout in powder form and mixes it with the soil in situ.

The wet method is used for soils with low water content: a tool injects the grout in slurry form under low pressure and mixes it with the soil in situ.

Soil mixing

What for?

Soil mixing is a simple technique, constantly being improved. It is easily adapted to the structure to be built and different soils.


- retaining terrain
- reducing settlement beneath constructions
- watertightness, to confine polluted soils for example
- soil stabilization, particularly to prevent liquefaction during earthquakes.

Realization of continuous trenches

This technique allows you to quickly realize and easily walls in the ground.
A slicer is specially equipped to perform soil mixing.
Soil mixing

Soil mixing
Realization of waterproof walls for a dike
© Cédric Helsly pour Soletanche Bachy

Realization of columns

Soil mixing
Reinforcement work under a railway platform
© Sandrine VILLAIN / Image&son-cnam

This technique can be used to reinforce defective floors without damaging them, and to consolidate railway track beds without having to remove the tracks.


A specific tool is inserted into a thin tube enabling drilling between the track’s sleepers.

When it emerges from the tube, the tool opens and bores soil mixing columns of larger diameter.

Soil mixing
Operation of the soil mixing tool © Soletanche Bachy

Realization of wall in soil mixing

The two rotary drums of the tool derived from the hydrofraise drill and mix the soil with the binder.

Soil mixing
© Romain Secco

Soil mixing

Soil mixing


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