The polyurethane injection method involves injecting single or dual-component polyurethane resins into cracks using specialized high-pressure injection pumps. Upon contact with moisture or water within the crack, the resin reacts and expands, increasing in volume multiple times. This expansion allows the resin to tightly fill the voids, effectively blocking any water ingress.
This technique is particularly effective even in the presence of active water leaks. Especially with reactive polyurethane resins, the material rapidly cures upon contact with water, forming an elastic, watertight barrier without causing damage to the structure.
Where Is Polyurethane Injection Most Suitable?
Polyurethane injection is commonly used in a wide variety of cracks, including:
- Static structural cracks
- Cold joints
- Construction joints
- Shrinkage cracks that appear over time
Before application, a proper assessment of the crack type, the direction of water ingress, crack depth, and environmental conditions is critical to ensure effectiveness.
This method is especially preferred when:
- The crack is actively leaking
- A long-term, permanent waterproofing solution is required
- Other repair techniques are insufficient
- Non-invasive application (no surface demolition) is desired
Key Advantages of Polyurethane Injection in Waterproofing
Polyurethane injection offers multiple advantages for effective waterproofing:
- Exceptional Sealing Performance: Expands upon contact with water to permanently seal the crack
- Elastic Behavior: Cures to a flexible material that accommodates structural movement
- Deep Penetration: Reaches even the finest capillary cracks
- Performs Under Active Leaks: Application is effective even when water is present
- Non-Destructive: No need for surface breaking or removal
- Fast Application: Saves valuable time on-site
- Chemical Resistance: Resistant to many aggressive agents and environments
Professional Application Steps of Polyurethane Injection
A successful injection begins with a professional, methodical approach:
- Crack Analysis and Surface Preparation
The crack area is visually inspected, mapped, and the injection zones are marked. - Drilling for Packers
Holes are drilled at 45° angles alternately on both sides of the crack, at pre-determined intervals. - Installing Injection Packers
Metal or plastic packers are securely anchored to the injection holes to prevent leakage. - Preparing the Polyurethane Resin
The appropriate resin type (single or dual component) is selected based on the crack type and water presence, then mixed. - Injection Process
Using high-pressure injection pumps, the resin is introduced into the crack through the packers, where it expands and fills the voids. - Curing and Post-Injection Checks
The resin expands, cures, and forms a waterproof seal. Once fully cured, the packers are removed. - Surface Cleaning and Final Inspection
Any excess material is cleaned, and a final water tightness test is performed to ensure a successful application.
Which Polyurethane Products Deliver the Best Performance in Concrete Crack Injection?
The quality of the polyurethane resin used plays a critical role in the outcome of the injection. One of the most reliable products in the field is Dryfix DF PUR Injection 2K, a high-performance, dual-component polyurethane resin developed for professional applications.
Key benefits of Dryfix DF PUR Injection 2K:
- Expands upon contact with water, effectively sealing voids
- Maintains high elasticity for long-term performance
- Rapid curing minimizes downtime
- Non-aggressive to reinforcement and concrete
- Suitable for negative pressure environments
It is particularly well-suited for structural elements such as retaining walls, foundation slabs, and underground water reservoirs.
Polyurethane vs. Epoxy Injection – What’s the Difference?
Although often confused, polyurethane and epoxy injections serve very different purposes:
| Feature | Polyurethane Injection | Epoxy Injection |
|---|---|---|
| Primary Use | Waterproofing | Structural repair |
| Flexibility | Elastic | Rigid |
| Surface Conditions | Wet or damp cracks | Dry cracks only |
| Crack Movement | Accommodates movement | For static cracks only |
In summary, when the goal is water sealing—especially in dynamic or leaking cracks—polyurethane is the preferred method. Epoxy is more suited for restoring structural integrity in dry, non-moving cracks.
Why Early Intervention Is Essential in Concrete Crack Repair
Ignoring even minor concrete cracks can lead to serious long-term issues, such as:
- Corrosion of reinforcement
- Reduction in structural strength
- Soil weakening due to water infiltration
- Decreased building durability
- Energy inefficiency
- Mold, mildew, and poor indoor air quality
Addressing cracks early with polyurethane injection minimizes repair costs and preserves the structural and environmental integrity of the building.
Polyurethane Injection: A Long-Lasting Waterproofing Solution for Concrete Cracks
In modern construction and repair practices, polyurethane injection stands out for its reliability, ease of application, and lasting performance. Partnering with trusted systems like Dryfix DF PUR Injection 2K ensures not only waterproofing but also long-term protection of your structure.
Stop chasing leaks—start applying solutions.
Get in touch with Dryfix to discover how professional polyurethane injection can restore your structure with confidence.
