Why Use Rigid Inclusions?

When Rammed Aggregate Pier elements cannot adequately control settlement in soft or loose soils, and there is a stiffer soil layer below the soft/loose soils, the use of Rigid Inclusions can typically solve the problem. Rigid inclusions are frequently used for soil stabilization when a load is being transferred through very soft soils to stiffer soil or rock, increasing load-carrying capacity and reducing compressibility of the poor soils. Rigid inclusions are often used to support an embankment or building over compressible soils, ultimately supported by a hard layer.

Rigid inclusions consist of cement-treated aggregate, grouted aggregate, grout mixed with soil, or concreted columns that are used to transfer the stress from the foundation or embankment loads through very soft soils down to stiffer soil or rock layers. While Rigid inclusions can be used as a singular solution for a project, they can also be used in combination with conventional rammed aggregate pier ground improvement methods to optimize both performance and project cost. Rigid Inclusion technologies include: Grouted Rammed Aggregate Pier System, Precision Grouted Rammed Aggregate Pier (RAPs), and GeoConcrete.

To create rigid inclusions, a hollow mandrel is used to penetrate the ground and displace weak soils laterally.  Either grout, grouted stone, or concrete is extruded from the end of the mandrel, or from multiple ports within the hollow mandrel. As the mandrel is gradually lifted, it leaves behind a rigid inclusion column of controlled stiffness.

To create rigid- inclusions, a hollow, dual flight auger is lowered from a crane as it spins.  Grout is then gradually added as the auger spins in reverse from the bottom of the cavity to the top of it, leaving behind a mixture of grout and soil to create a rigid inclusion. Factors driving the design of all rigid-inclusion systems include the following considerations: poor soil depth, the geotechnical capacity of stiff soil at depth, the structural capacity of the Rigid inclusion, and the structural loads being applied.

Grouted Rammed Aggregate Pier Systems
Precision Grouted Rammed Aggregate Piers
GeoConcrete Columns
Drilled Displacement Columns
Armorpact (Confined Rammed Aggregate Piers)

Rigid Inclusion Applications

• Isolating Stress from Heavily Loaded Footings
• Supporting Heavily Loaded Mats and Slabs
• Embankment or Wall Support in Very Poor Soil
• Ground Improvement for Thick Organic and Peat Layers
• Providing Foundation Support Adjacent to Below-Grade Structures
• High Capacity, Engineered Approach where Rammed Aggregate Alone will not Suffice.