There are different methods for grouting, and together they make up for a considerable part of ground improvement and/or existing foundation strengthening methods overall. A particle or chemical based grout usually with additives is injected into the soil with different placement techniques. The additives include lime, portland cement, fly ash, bitumen or their combinations. Grouting may be used alone or sometimes it may be used in combination with compaction. The goal is to obtain a hardened cementlike soil, which is much denser, stronger and resistant to water flow. Each differ in the way the are applied, the exact materials used, the type of soil and the condition of groundwater, cost, schedule and equipment considerations, available workspace, limitations resulting from environment or immediate surrounding area (if any), and of course the desired result. But we will not go into details of those. We will just list the names of them along with brief descriptions, for interested readers to research further:
- Permeation grouting: injection of chemical based grout, to make a solid soil mass.
- Compaction grouting: mortar grout is injected into the soil on certain intervals, forming columns of grout bubbles, which not only serve as columns in the soil but also compacts the surrounding soil by pushing them away.
- Cement grouting: fills cracks and voids in coarse grained soils, to create a mass of cemented soil.
- Compensation grouting: injection of cement slurry grout into the soil with pressure, usually below an existing footing, to fill the voids and cracks in the soil and then to start lifting the foundation. Also can be called fracture grouting.
- Jet grouting: applying high velocity jet of cement grout to create solid columns within the soil mass.
- Polyurethane grouting: Polyurethane grouting involves injection of expanding polyurethane to fill and seal cracks and voids and re-level foundations or slabs. It is also good for creating a watertight barrier under slabs.
In the next post of this series, we will discuss “Soil Compaction Methods”