![](https://research.engineering.ucdavis.edu/gpa/wp-content/uploads/sites/43/2015/02/Schematic-HBaker-11-300x296.jpg)
This series of schematics illustrates the general procedures in the bottom-up technique of compaction grouting. The first step, shown here, is to install grout pipes using drilling or driving techniques.
![](https://research.engineering.ucdavis.edu/gpa/wp-content/uploads/sites/43/2015/02/Schematic-HBaker-21-300x295.jpg)
The mortar-like grout, injected through the pipes, displaces the surrounding soil. The grout pipe is then lifted some distance (0.3 to 1.5 m), and the injection process is repeated.
![](https://research.engineering.ucdavis.edu/gpa/wp-content/uploads/sites/43/2015/02/Schematic-HBaker-3-300x295.jpg)
Injection in “stages” continues until the target layer has been treated. Grouting can stiffen and strengthen the soil layer by increasing its density, increasing the lateral stresses, and acting as a reinforcement. Grouting may also be used to produce controlled heaving of the ground surface to re-level a structure that has been damaged by differential settlements.
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![Grout bulbs-1](https://research.engineering.ucdavis.edu/gpa/wp-content/uploads/sites/43/2015/02/Grout-bulbs-1-204x300.jpg)
These compaction grout bulbs were excavated as part of a demonstration project by Denver Grouting (now with Hayward Baker). These four grout bulbs were from the same grout mix, and are all relatively regular in shape.
![Grout bulbs-2](https://research.engineering.ucdavis.edu/gpa/wp-content/uploads/sites/43/2015/02/Grout-bulbs-2-203x300.jpg)
These four grout bulbs were from a more “mobile” (more fluid like) grout mix which allowed it to form winged-shaped bulbs.