Low mobility (compaction) grouting densifies loose soils, reinforces fine-grained soils, and seals subsurface holes by injecting low slump grout.

Common Uses

  • Mitigate liquefaction
  • Reduce soil and structure settlement
  • Improve bearing capacity
  • Secure sinkholes or decrease sinkhole potential

Technical Details

Low mobility grouting (also referred to as compaction grouting and low mobility displacement grouting), delivers low mobility grout via open-ended tubes (drill casings) drilled or driven to pre-determined depths. The grout typically contains cement, sand, fly ash, and water and is placed in stages, from the bottom of the hole upwards using pressure- and volume-based refusal criteria. Between consecutive stages, the casing is retracted upwards until the delivery tube is completely removed. The low mobility grout displaces the existing soil creating grout bulbs in situ. Benefits of this process include densification and consolidation of the soil and creation of vertical grout columns.

Stage dimensions and volume refusal criteria are determined on a hole by hole basis, after drilling, but prior to grouting. Grout injection rate and pressure are dictated by the soils' ability to redistribute the increased stresses and dissipate pore water pressures and are often modified as the grouting program progresses.

As the technique involves displacement, it is particularly effective in disturbed soils. Most of Keller’s past compaction grouting jobs have been because of our clients’ need to repair disturbed soil for reasons such as over-excavation during tunnelling, long-term migration of fine particles through broken sewer pipes, water main rupture, or past poor compaction of placed fill soils.