Insitu soil mixing has numerous cost-effective applications for civil infrastructure projects and environmental remediation. Special equipment and tools are used to mix soil or sludge with a cement grout or other reagents to improve their properties or treat buried contamination. Insitu soil treatments can be used to strengthen soft soil formations, volatilize or oxidize contaminates, stabilize sludge, mix and inject biological or reactive media, and to implement a wide variety of other insitu treatments.
Insitu soil mixing has the significant advantage of treating soils without excavation, dewatering, or shoring. But the process involves bulking of the treated material, which can exceed 30 % depending upon the nature of the soil.
Insitu soil mixing is often classified into two categories depending upon the depth of treatment:
• Shallow Soil Mixing, or SSM, for treatment depth within the first 25/35 feet.
• Deep Soil Mixing, DSM, for greater depth. Soil mixing has the capability to go to depths greater than 100 feet.
Backhoes equipped with special tools, multiple augers, large diameter augers and other specialized equipment, such as the CSM, are used for mixing in situ the soils with the reagent. The equipment selection will depend upon the depth of treatment as well as the nature of the materials to be treated.
Insitu soil stabilization has also been used to build retaining walls, cutoff walls, and other foundation systems.
The design of an insitu soil mixing project requires a comprehensive understanding of the site conditions and the goals to achieve. Usually, a pre-construction laboratory testing program is enacted to establish performance criteria, material requirements and budget costs. The testing may be used to determine workability, volume increase, strength, permeability, leachate chemistry or biological characteristics of the treated soils. A pilot program, or field test, can also be implemented to better determine the specifics of the project. A well-designed laboratory program and/or pilot program will usually provide an accurate prediction of project performance.