Compaction grouting involves the injection of a low slump, mortar grout to densify loose, granular soils and stabilise subsurface voids or sinkholes.

Keller rig performing compaction grouting

Common uses

Suitable for rubble fills, poorly placed fills, loosened or collapsible soils, soluble rocks and liquefiable soils
Often selected for treatment beneath existing structures because the columns do not require structural connection to the foundations
Decrease or correct settlement
Increase bearing capacity
Stabilise sinkholes or reduce sinkhole potential

Process

An injection pipe is inserted, typically to maximum treatment depth, and the grout then injected as the pipe is slowly removed in lifts, creating a column of overlapping grout bulbs. The expansion of the grout bulbs displaces surrounding soils and the grouting increases the density, friction angle, and stiffness of surrounding granular soils.

You can increase effectiveness by sequencing the compaction grouting from primary to secondary to tertiary locations. In all soils, the high modulus grout column reinforces the treatment zone.

Advantages

Often more economic than conventional approaches such as removal and replacement, or piling
Can be done where access is difficult and in limited space

Quality assurance

Keller can provide complete solutions which combine compaction grouting with real-time monitoring of affected structures, and has a variety of rig types to accommodate access constraints.