Slurry grouting is used for stabilization of shallow soils by solidifying and binding the fine soil particles together. The slurry grout permeates the soil particles and cements them together to make the soils less mobile and more stable. Compaction grouting in comparison is used to densify and replace soils.
Slurry grout is normally a shallow application less than 20 feet in depth and routinely averages 10 feet in depth. The reason that slurry grout is used in conjunction with compaction grouting is that during the higher pressure compaction grouting process we stop at 20 feet in depth in order to avoid heaving or damaging the structure. There are other forms of shallow soil stabilization such as chemical grouting and polyurethane foam injection. Each one of these materials has specific use depending on the soil makeup and engineering specifications.
The Slurry Grouting Process:
The slurry grout material consists of Type1 or Type 2 Portland cement mixed with water. The mixing process, depending on the size of the job and the quantity of material desired, is either done on-site with a tub mixer or it is ordered by the truck through a concrete producer. This material is pumped into injection points whose location is determined by the engineer. The material typically has a 10-12 inch slump which is highly liquid in nature which allows the cement to permeate the soil particles and bond them together. The injection points are normally spaced between 6 and 8 feet apart on center in either a linear or grid configuration. They are installed to depth per the engineers recommendations based on the soil profile encountered. The injection points are hammered or drilled to depth.
Once the injection points have been properly installed the slurry grout material is pumped, normally with a progressive cavity mono-pump, and pressures are monitored not to exceed 65 PSI. The mono-pump delivers material at a slow continuous rate in order for the slurry grout material to properly permeate the soils at low pressure. This keeps the soils from fracturing and veining and allows us to monitor the structure itself to prevent any heaving or movement.
During the slurry grout procedure the pipe is extracted in 1 foot intervals when we reach the desired pressure and the hole is then grouted all the way to the surface.
Think about slurry grouting as making the soils hard without consolidating and compacting the soils.
Slurry grouting is used for many problems throughout the world such as erosion control, sealing and repairing dam and dikes, preventing water intrusion and for repairing and sealing culverts and spillways.
The NEC Keystone Difference
We use specialized equipment for use on slurry projects including our mono-pump delivery system (most other companies try to do the job with a concrete pump).
We use the proper injection rods (J-Rods) which are specifically designed for slurry applications.
We install the injection rods with specialized drilling equipment that is designed for the slurry procedures (most companies use their standard drilling equipment)
We have the best trained personnel to complete the task properly with a minimum of disruption.
We have completed slurry grouting projects all over the state from Leon, Hamilton and Columbia counties in North Florida down to Miami Dade, Broward and Palm Beach Counties in South Florida.