Compaction Grouting is a type of Pressure Grouting that densifies and compacts soil that is in need of stabilization.
Arizona Foundation Solutions is the leading contractor for underpinning in the State of Arizona for several years now; and have helped thousands stabilize and raise their sunken foundations. However, there are times when there are structures that needs to be stabilized and or lifted and helical piers are not a viable option because the structure is not capable of the point stresses that are involved with piering. By driving an injection pipe deep below the surface and then pumping various types of grout, the soil itself can be stabilized and even be made stiffer and denser.
The process is similar in practice to slabjacking, however instead of grouting only under the slab or filling the hole we drive the tube to a predetermined depth, and pressure grout the weak soils making them more stable. This also can be beneficial to fill voids in very rocky soils that traditional piering may not be suitable for.
In order for this type of repair to be effective deep soil testing must be done by a competent soils testing engineer. An effective grouting plan can then be designed that will take into effect the various layers of soil and their densities to avoid injecting on top of loose soil and exacerbating the problem by adding weight on top of the incompetent soil. We have successfully grouted pavements, building slabs, bridge approach slabs, house floors, pools and other simliar types of infrastructure.
Soil Stabilization using grouts:
Compaction grouting is the controlled injection of low-slump, lo mobility, soil/cement grout into the subsurface soils. The intent of the grouting program is to compact loose, coarse-grained soils and displace and/or densify fine-grained soils. The grout is injected at designed depths and locations in a grid pattern at high pressure. As a result, the viscous grout forms into a bulb or column at the desired depth, displacing the soil, densifying it, resulting in improved bearing capacity.
Low Mobility grouting
CLSM -Cementious Grouting, is the intrusion under pressure of flowable particulate grouts into open cracks and voids and expanded fractures to improve its strength or reduce permeability. Cement grouting is most commonly performed by drilling holes into the foundation to intercept open racks, joints, fissures or cavities, then pumping under pressure balanced and stabilized grout mixes using a combination of cement, water, and additives. Work generally begins with a base mix and is modified during the grouting process with subsequent mixes in order to achieve closure by reducing permeability to a predetermined value.
Intrusion/Prementation Grouting is a procedure in which a very high cement ratio grout is injected into the soil under pressure to cause controlled fracturing of the soils. Upon initial grouting, fractures develop along the planes of weakness, which may be bedding planes or minor principal stress planes. Repeated injections tend to cause fractures along different planes which causes the soil to harden.
Cellular Concrete is an effective combination of Geo foam, an advanced foaming agent and cement slurry. GEOFOAM is a modified aqueous concentrate of a surface-active Polypeptide-Alkylene polyol condensate, specially formulated to yield a stable, voluminous micro bubbled foam. The foam is used for producing cellular or foamed concrete used for the replacement of unstable soils, density controlled load relief, and void fills while increasing compression and sheer strength.
Pressure Grouting Installation
1. First drive the injection casing to the proper depth. This can be done in one of several ways. The simplest is to hammer down the casing with an air powered driver or a hydraulic powered hammer. Sometimes when penetration through harder soils is required to reach unconsolidated soils pre-drilling is required. Usually with a down in the hole hammer. This is a common step that is often not followed with vigilance.
2. Once the proper depth has been reached. Grout is pumped down and injected. For Compaction grouting, a very stiff mix with in internal high friction is used. For true compaction grouting a 2" diameter or larger casing is required. Any casing less than 2" is not true compaction grouting. Grout pressure and volume should not be large enough to fracture the soil.
3. Once a volume, pressure or ground movement marker has been met, the casing is raised 12 to 24 inches and the same grouting process is repeated.
4. This grouting and lifting procedure is repeated until the surface is reached.
Compaction or slurry grouting is a process that should be done under the direct supervision of a licensed geotechnical engineer who is independent of the contractor.
What pressures or volumes should each injection at a particular depth of soil be stopped at?
Owners do not have the knowledge to make such decisions and contractors have too much conflict of interest to make those determinations.
Geotechnical borings should be done in advance of any grouting to help the Engineer make sound decisions. The engineer should then inspect the process to insure that his parameters are followed and sign off and stamp the project on completion.
More Pressure Grouting Information
Read more about sink hole issues on this latest Fox News Report
We have successfully grouted pavements, building slabs, bridge approach slabs, house floors, pools and other simliar types of infrastructure. Our crew is talanted, hard working, and careful.
As you run into soil problems of any type, please call and challenge us to bring you the right soultion to each problem.