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

Typical applications

  • 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.

Key benefits

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