Trench cutting and remixing deep (TRD) soil mix walls are mixed-in-place using a specialised vertical cutter post mounted on a base crawler machine.

Trench cutting and remixing deep (TRD) illustration

Common uses

Create barriers to groundwater flow
Support excavations


The vertical cutter post, resembling a large chain saw, is inserted vertically in sections by the crawler machine until the design depth of the wall is reached. The crawler machine then advances along the wall alignment while the cutter post cuts and mixes the in situ soil with cement-based binder slurry injected from ports on the post. The vertical mixing action blends the entire soil profile, eliminating any stratification and creating a soil mix wall.


High degree of uniformity
Low permeability
Very consistent mix so designers can count on same strength top to bottom
Very vertical wall (TRD has inclinometers in the post)
Continuous mixing horizontally
Less materials versus total excavation
Environmentally friendly
Very stable trench and very low chance of tip over

Quality assurance

We can ensure quality through:

  • Continuously checking binder at the plant and TRD (Specific gravity, temperature, flow rate)
  • Data acquisition to show exact quantity of product installed for each metre of wall
  • Constantly monitoring verticality
  • Checking the workability of the mix with a flow table twice per shift
  • Taking wet samples at any depth and checking for strength permeability or other requirements
  • Coring the wall to check wall consistency
  • Upfront Bench Scale testing of mix and soils