What is Compaction Grouting?
Compaction grouting is a process of stabilizing the soil prior to construction. This is accomplished by drilling to a pre-determined depth below the surface and injecting a low-slump, low-mobility soil/cement grout into the ground. The grout mixture creates a pocket deep below the surface that grows as more grout is forced into the ground. As the pocket of grout expands, it compacts the soil around it, causing it to become more stable for the building. In almost all cases, several “stacked” pockets of grout are created, stabilizing the soil over a depth that will support the intended structure.
Compaction Grouting Installation
Compaction grouting is typically performed in a sequenced operation over a pre-defined grid pattern. At each location, the casing is driven or drilled to design depth and grouting is performed from the bottom up in short lifts of typically 1-2 ft until a predetermined refusal criterion (maximum pressure, maximum grout volume, or maximum structural surface settlement) is met. The grout pipe is then raised to the next stage and the process is repeated to form a grout “column”. Grout column installation in a primary/secondary /tertiary sequence displaces and thus densifies the intermediate soils.
Compaction Grouting Utilization
Compaction grouting builds up the ground; it is utilized to stabilize underground formations for pipes and tunnels. It can also hold foundation settlement, improve bearing capacity of soils, and manage sites with sinkhole activity.
The following can use compaction grouting subsurface conditions.
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Sinking or settling formations
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Sinkholes
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Weak soils
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Inadequately compact fills
Advantages of Compaction Grouting
Compaction Grouting can manage the settlement of foundations on existing homes; stabilize subsoils that are defined to be weak before starting construction on a new home or structure, and lifting existing foundations that have settled.
Here are some advantages of Compaction Grouting:
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Rapid installation
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No spoil generation
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Can be accomplished in restricted access situations
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Structural foundation connections not required
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Low mobility grout rheology allows for precisely controlled placement
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To increase bearing capacity
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To arrest or reduce foundation settlements
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Mitigation of liquefaction potential
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Sinkhole remediation
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Stabilization of karstic formations