Compaction Grouting and Foundation Repair
Compaction Grouting is the stabilization of poor soils under buildings, structures, roadbeds, railroads, or runways, by driving injection pipes down to stable ground and then injecting low-mobility grout to densify soft soils and form grout columns. Injection is continued in a pattern to cover all of the target area until the ground, building, or slab is raised back to original elevation, eliminating all voids. The amount of grout injected and pressures at each lift are closely monitored on every hole to adjust for differing soil conditions for quality control.
Foundation repair - Compaction Grouting is an excellent alternative to helical piles in raising foundations for several reasons:
- With helical piles excavation is needed to get under the foundation far enough to try and drive piles as vertical as possible and then to get jacks underneath with a bracket to lift the foundation. Most foundations are designed to have continuous contact with the ground to be stable.
Compaction grouting injection pipes are driven in from the surface and slightly angled to reach stable soil under the foundation. When the soft soils are densified and stabilized, the ground, along with the building is raised. Injection pipes are removed as injection continues and no backfill is necessary.
- With helical piles, there is point loading on each pile and as the foundation is jacked up, voids are created between the piles under the foundation. Also if there is a slab-on-grade attached, voids will be created or increased, putting more stress on the slab. All voids should be grouted and the slab raised in an additional operation to stabilize the rest of the foundation.
Compaction grouting densifies the soft soils and raises the foundation by raising the ground so there are no voids and no point loading. Injection pipes can be angled to reach up to 20' from perimeter walls, depending on soil conditions. In very poor soil conditions interior slabs can also be compaction grouted to stabilize the ground and raise the slabs.
- With helical piles, there is usually much more time involved due to excavation, inserting piles, jacking foundation, backfilling, and then grouting the voids.
With Compaction grouting we can often drive injection pipes and grout the same day for a typical garage size building.