The term permeation means the process of diffusing through or penetrating something. Single part permeation grouting is a procedure used for soil stabilization, consolidation and penetration. Single part permeation grouting uses the technology of a single part hydrophobic polyurethane chemical to permeate the soil while encapsulating and strengthening the soil mass, improving the density of the subsurface soils and increasing load bearing capacity in order to prevent future soil consolidation and movement.
The industry standard to date for a single part polyurethane grouting solution has been to install either an open-ended injection pipe similar to that used in two part polyurethane grouting or the use of a
manchette (strainer pipe). The chemical product manufacturers such as DeNeef and NCFI have traditionally recommended the use of a Titan airless paint sprayer pump to deliver the material. The problem with this procedure is the lack of control over delivery volume and pressure along with no verification for the actual amount and rate of material being injected into the soil. Under this injection method the only way to regulate the amount and rate is the use of an open 5 gallon bucket which exposes the chemical product to humidity throughout the entire repair process. This affects the viability, viscosity and reaction time of the material.
NEC Keystone has developed a new process and equipment for the injection of a single part polyurethane to achieve the most reliable and accountable repair. NEC Keystone’s new process allows exact control and monitoring of the pressure, rate and volume of material used during the injection process. The additional data and control are communicated to the engineer throughout the repair procedure. This allows NEC Keystone and the engineer to deliver the single part polyurethane material in the most optimal way to execute the best possible repair at the lowest cost.
The NEC Keystone Difference
1. We build our manchettes with a welded on pointed tip to keep soils from intruding during installation which could prevent optimal material flow. They are built 16” in order to insure a 30% overlap when retracted 12” at a time during the injection process in order to form a continuous permeated grout column. Normal 12” have no overlap built into the design.
2. Once the pipe and manchette(strainer pipe) are installed per the engineers specifications, it is a critical part of the procedure to purge the pipe under high pressure before injection and make sure the pipe is clear of all soil and debris. NEC Keystone uses an in line pressure gauge as part of the purging gun at the injection port to monitor back pressure during this part of the procedure. This insures the free flow of the single part polyurethane material during the injection process.
3. The injection guns are designed by NEC Keystone to accurately monitor the pressure at the injection port in order to prevent injury, spillage and damage to the property. This provides a safe and clean workplace. Our system also provides a more effective and efficient delivery method then the standard ball valve injection process.
4. We meter exact quantities of injected materials during the repair process with the use of an electronic digital flow meter that has been designed by the manufacturer for these materials and procedures. The flow meter can be calibrated and verified prior to the repair process. NEC Keystone’s use of the flow meter precisely documents the amount of permeating grout material used during the repair process. The flow meter gives the engineer data on material used at every depth and total per point as well as the flow rates at each depth which gives the engineer the profile of the soil, rate of absorption and time per interval at each point and depth.
5. The flow rate of the material is also precisely controlled during the entire repair with the use of a material flow control valve. The valve has the capability to control the single part material from 0 to 5 gallons per minute within a one ounce interval providing exacting control of the single part polyurethane material into the soil mass. The engineer can adjust flow rates based on current soil conditions.
6. We regulate the pressure of our system between 0 and 300 psi per the engineer’s recommendation. These pressures are held constant and do not fluctuate. This insures total control of the single part polyurethane material during the procedure. The engineer can easily view and adjust the pressure based on the actual soil conditions during the repair process.
7. The chemical grouting material is delivered and mixed in a self-contained, closed system. Moisture and humidity do not come into contact with the single part polyurethane material to insure consistency and the highest quality of deliverable material. At no time are the chemicals exposed to the environment. There is also no human exposure to the polyurethane chemical further increasing worker and engineer safety.
8. During the injection process NEC Keystone uses a Stanley zip level to monitor the interior floors along with a laser level monitoring the exterior walls to insure detection of any movement of the structure.
9. Unlike other companies NEC Keystone extracts all injection pipes during the process. Leaving any pipe or foreign materials in the ground may create a future hazard.
10. The NEC Keystone Approach allows us to speed up the installation time of a normal permeation grouting job. The NEC Keystone Approach also reduces waste and allows fast and accurate delivery reducing both cost and time. There is also no oversaturation which further reduces material costs.
11. We have surpassed all industry standards in accountability and verification with our approach. The NEC Keystone Approach has overcome the current short comings of the industry standards for permeation grouting by giving the engineer full control of the installation and monitoring process. Delivery system with exacting control of the repair process.