Services > Ground Improvement > Soil Mixing

Soil Mixing-Dry Method Soil Mixing - By The Single-Axis Tool Method Soil Mixing, also known as the Deep Mixing Method, is the mechanical blending of the in situ soil with cementitious materials (reagent binder) using a hollow stem auger and paddle arrangement. The intent of the soil mixing program is to achieve improved character, generally a design compressive strength or shear strength and/or permeability. Soil mixing can also be used to immobilize and/or fixate contaminants as well as a treatment system for chemical reduction to a more ‘friendly’ substrate.

Dry Soil Mixing Process
Using specialized mixing tools, the soil is premixed during penetration, until the mixing tool reaches the maximum treatment depth. Dry binder agents are then injected directly into, and mixed with the soil during withdrawal of the mixing tool, leaving behind a dry soil mix column. Within a few hours after mixing, the treatment area is preloaded with several feet of soil surcharge to provide confinement during curing. After curing for 2 to 6 weeks the soil will be 10 to 50 times stronger, and much stiffer.  

Binder Agents
The strength of the soilcrete develops differently with time depending on the type of soil and the amount and type of binder being used. Binder agents may include:

• Cement
• Lime
• Gypsum
• Slag

Dry Soil Mixing Applications

• Foundation Support
• Tunneling Support
• Liquefaction Mitigation
• Port Development
• Slope Stabilization

Geotechnical Considerations
In most cases, Dry-SM works well in high moisture content (>60%) silty and clayey soils. Organic soil and peats can often be stabilized, but laboratory testing is always recommended prior to design.

Quality Assurance/Quality Control
To assist in monitoring and controlling the installation process Dry-SM rigs are fully instrumented with an on-board computer system to monitor binder dosage and drilling parameters. The following information is documented prior to and during construction: