Polyjacking, also known as foam jacking, is a construction method used to lift and level settled or uneven concrete slabs. This method involves injecting polyurethane foam underneath the sunken concrete, expanding to fill voids and raising the slab. Polyjacking is valued for its speed, minimal disruption, and durability in comparison to traditional mudjacking methods.
Different techniques used for polyjacking
Different techniques are used for slabjacking, each of them are explained below;
1. Slabjacking:
Slabjacking involves injecting polyurethane foam beneath concrete slabs to lift and level them. This method is particularly suitable for surfaces like sidewalks and driveways. The process is relatively quick and minimally invasive, making it a cost-effective solution for addressing uneven or settled concrete slabs. The injected foam expands, filling voids and providing structural support, ultimately restoring the integrity of the surface.
Polyurethane foam injection is a key component of the slabjacking process. This innovative method utilizes high-density foam that is injected beneath the concrete slab to achieve the desired lift and level. Unlike traditional mudjacking, polyurethane foam injection is lightweight yet strong, expanding rapidly to fill voids and stabilize the foundation.
2. Permeation Grouting:
Permeation grouting utilizes polyurethane foam injected into the soil to fill voids and compact loose or weak ground. This method significantly improves soil stability and enhances load-bearing capacity. By permeating the soil, the foam creates a solid foundation, preventing settling and ensuring a stable base. Permeation grouting is commonly employed in projects where ground improvement is crucial for the overall structural integrity.
3. Compaction Grouting:
Similar to permeation grouting, compaction grouting involves injecting polyurethane foam into the soil. However, in this method, the goal is to densify and stabilize loose or settling soils. It is often used for underpinning foundations, providing increased strength to the soil and mitigating issues related to settlement. Compaction grouting is an effective solution for reinforcing the ground beneath structures, ensuring long-term stability.
4. Void Filling:
Polyjacking for void filling is used to address empty spaces or gaps beneath structures. The injected polyurethane foam serves the dual purpose of providing support and preventing further settling. This technique is particularly useful for structures experiencing issues due to voids in the soil or empty spaces beneath concrete slabs, ensuring structural integrity and stability.
5. Piling with Polyurethane Injection:
Piling with polyurethane injection combines foundational support structures like helical piles with polyjacking. Helical piles offer foundational support, while polyurethane foam is injected to stabilize the surrounding soil and fill any voids. This method provides a comprehensive solution, addressing both foundational and soil stability aspects, making it versatile for various construction projects.
6. Lateral Injection:
Lateral injection involves the horizontal injection of polyurethane foam to stabilize soil or fill voids beneath a structure. This technique is particularly useful in addressing challenges such as soil erosion. By injecting foam laterally, it effectively reinforces the soil, preventing lateral movements and maintaining the structural integrity of the surrounding area.
7. Sequential Injection:
Sequential injection is a controlled method where injections are performed in a sequence to lift different sections of a structure gradually. This approach ensures an even and controlled lift, making it suitable for complex projects where precision is essential. By carefully managing the sequence of injections, the structure is lifted uniformly, minimizing the risk of uneven settling.
8. Undersealing:
Undersealing involves injecting polyurethane foam under a structure to provide support and fill gaps. This technique is commonly used to address settlement beneath foundations. The injected foam fills voids, stabilizes the soil, and supports the structure from below, effectively preventing further settling and maintaining structural integrity.
9. Hydraulic Lifting:
The hydraulic lift method utilizes polyurethane foam injected through hydraulic systems for controlled and precise lifting of structures. This method is particularly advantageous in situations where accuracy is crucial. The hydraulic system allows for careful adjustments, ensuring that the lift is precisely controlled, making it suitable for projects with stringent elevation requirements.
10. Deep Injection:
Deep injection involves injecting polyurethane foam at greater depths into the ground to improve soil density and provide support. This method is employed when stabilization is required at significant depths. By enhancing the soil’s strength deep below the surface, deep injection ensures robust support for structures, making it a suitable solution for projects with specific depth-related challenges.
Uses of polyjacking
- Lifts and levels settled or sunk concrete foundations, providing structural support.
- Levels concrete slabs for improved evenness and safety.
- Fills voids beneath concrete structures, preventing further settlement and enhancing stability.
- Enhances load-bearing capacity of soil by injecting foam, strengthening weak or loose soils.
- Supports and stabilizes underground pipelines and utilities to prevent shifting or damage.
- Repairs infrastructure like bridges and roadways, addressing settlement issues.
- Used for underpinning foundations, reinforcing and stabilizing for additional loads.
Application method for polyjacking
1. Site Inspection:
- Assess the affected area to identify the extent of settlement and any potential causes.
2. Preparation:
- Ensure proper safety measures are in place.
- Clean the surface of the concrete to be treated.
3. Drilling Holes:
- Use a drill to create small-diameter holes in the settled concrete. The hole placement depends on the specific conditions of the area.
4. Installation of Injection Ports:
- Insert injection ports into the drilled holes. These ports will serve as entry points for the polyurethane foam.
5. Mixing the Polyurethane Foam:
- Prepare the polyurethane foam mixture according to the manufacturer’s instructions.
6. Foam Injection:
- Connect the injection gun to the ports.
- Gradually inject the polyurethane foam into the voids beneath the concrete.
- Monitor the foam’s expansion and adjust injection rates as needed for even lifting.
7. Lifting and Stabilization:
- Observe the lifting process and ensure that the settled concrete is raised to the desired level.
- Stop injection once the desired lift is achieved.
8. Sealing Ports:
- Remove the injection ports and seal the drilled holes using an appropriate material.
9. Clean-Up:
- Clean the work area, removing any excess foam or debris.
10. Curing:
- Allow the injected polyurethane foam to cure and harden. The curing time may vary based on the specific product used.
11. Quality Check:
- Inspect the lifted concrete to ensure it’s stable and level.
- Address any additional issues or concerns.
Applications of polyjacking
- Sidewalks and Walkways
- Driveways
- Patios and Decks
- Garage Floors
- Pool Surrounds
- Warehouse Floors
- Industrial Facilities
- Airport Runways/Taxiways*
- Highway and Road Repairs
- Railway Platforms
- Residential and Commercial Building
- Municipal Infrastructure
Conclusion
Polyjacking emerges as a cost-effective method for addressing various concrete settlement issues. Its ability to lift, level, and stabilize foundations, coupled with minimal disruption and environmental impact, makes it a preferred choice for repair and rehabilitation. As the construction industry continues to evolve, the proven efficacy of polyjacking positions it as a valuable method for efficient, sustainable, and resilient concrete solutions.
