What is PU Injection?
PU injection, also known as polyurethane grouting or injection, is a waterproofing technique that uses expanding injected polyurethane to seal cracks and voids in concrete structures, preventing water leakage. This method involves injecting a fluid polyurethane resin into cracks, fissures, or other voids within concrete. Once injected, the polyurethane expands, filling the spaces and creating a watertight seal.
The process typically involves drilling small holes into the concrete structure near the affected area. A specialized nozzle is then inserted into these holes, and the polyurethane resin is injected under pressure. The resin's expansion fills the cracks and voids, effectively blocking the passage of water.
- Step 1: Assessment and hole drilling
- Step 2: Nozzle insertion
- Step 3: Polyurethane injection under pressure
- Step 4: Expansion and sealing
Advantages of PU Injection
- Effective waterproofing: Creates a strong, durable seal against water penetration.
- Accessibility: Can reach inaccessible areas and cracks.
- Minimal disruption: Often requires minimal demolition or surface disruption.
- Versatile: Suitable for various concrete structures and crack types.
- Fast curing: The polyurethane typically cures quickly, allowing for rapid project completion.
Applications of PU Injection
PU injection is widely used in various applications, including:
- Building structures: Repairing cracks in walls, foundations, and slabs.
- Parking garages: Sealing cracks to prevent water damage.
- Tunnels: Sealing cracks and joints in tunnel linings.
- Bridges: Repairing cracks in bridge decks and supports.
- Water tanks: Sealing cracks to prevent leaks.
Types of Polyurethane Used in Injection
Various types of polyurethane exist, each suited to specific applications and crack conditions. For instance, hydrophilic polyurethane resins are used for low-pressure crack injection.
Considerations
While PU injection is highly effective, it's important to note that the success of the method depends on factors such as the size and type of cracks, the pressure used during injection, and the skill of the applicator. In some cases, it may not be a suitable solution, and alternative methods might be needed.
