Compaction or low mobility grouting (LMG) involves the pressurized injection of a mortar-like, low slump grout to create bulbous masses which displace and densify the surrounding soil. Compaction grouting is commonly used to increase bearing capacity, arrest or reduce foundation settlements, mitigate liquefaction potential, remediate sinkholes, or stabilize karstic formations.
LMG can be used to meet a range of project objectives. When the intent of the grouting program is to densify the surrounding soils, LMG is better known as compaction grouting. The technique can be accomplished in low-headroom or restricted access conditions, often with minimal disruption to normal facility activities.
Compaction grouting is typically performed in a sequenced operation over a pre-defined grid pattern. At each location, 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.
- To increase bearing capacity
- To arrest or reduce foundation settlements
- Mitigation of liquefaction potential
- Sinkhole remediation
- Stabilization of karstic formations
- Rapid installation
- No spoil generation
- Can be accomplished in restricted access situations
- Structural foundation connections not required
- Low mobility grout rheology allows for precisely controlled placement
- Not appropriate for low permeability soils (i.e., clays).
- Not suitable in zones where limited soil cover can result in unacceptable heave.