Injection techniques are essential for strengthening and protecting structures and underground construction through ground consolidation, stabilization, and waterproofing. This article explores how injection works, its key applications, materials, and the benefits of using injection as a reliable solution across construction, tunneling and mining projects.
What Is Injection and How Does It Work
In the construction industry, injection is a technique used to fill cracks, joints, or cavities in the ground, concrete, reinforced concrete structures, or masonry by pumping or pressing mineral or synthetic resin-based products into them.
Typically, the material is applied through injection packers installed in the structure, for example within rock, soil, sand, concrete or masonry structures.
Rock, soil or sand
Masonry structure
Concrete structure
Once the material is injected, it undergoes a specific chemical reaction. Some products react with water or moisture to form a fast-expanding foam, effectively stopping flowing water.
Injection is often the only effective solution to repair an existing structure with water leakages.
Key Applications for Injection
Renovate / repair existing structures with leakages
- Structural crack repair
- Water stopping/ waterproofing of cracks, joints and cavities in masonry or concrete
- Damp proof courses in masonry
- Area and curtain injections
Protect new structures against water infiltration
- Water stopping/ waterproofing of cracks, joints and cavities
- Sealing of pipe ducts
- Structural crack repair
- Area and curtain injections
- Injection hoses
- Membrane compartment systems
Pre-excavation grouting / stabilization
- Proactively establish dry, stable, and safe ground as a preventive measure before excavations or erecting structures
Post-injection
- In concrete or in the ground.
- D-walls, sheet pile walls, bore pile walls – waterproofing
- Water stopping, waterproofing or consolidation in tunneling and mining
Main Injection Materials and Their Most Common Uses
Concrete / Masonry Structures
Repair Work / Waterproofing
Rigid
- Epoxy
- Cement
- Structural Polyurethane (PU)
Key Uses: Cracks and joints, structural repair
Flexible
- Polyurethane (PU) - Resin or foam
- Acrylate
Key Uses: Water stopping in cracks, joints, cavities, masonry, curtain, compartments
Tunnels / Mines (Underground)
Soil / Rock / Sand
Consolidation
- Polyurethane (PU) - Resin or foam
- Acrylate (sand)
- Anchoring Silicate and Thix
- Cement / Co. Sil
Key Uses: Stabilizing, void filling, consolidating
Waterproofing
- Polyurethane (PU) - Resin or foam
- Acrylate (sand)
- Silicate
Key Uses: Waterproofing up to huge amounts of heavily pressing water
Advantages of Injection Waterproofing
Injection can permanently seal even the smallest cracks and voids, providing a comprehensive waterproofing solution.
The materials used for injection can adapt to the movement and settling of the structure or the ground. Injection can be applied at any time— whether during initial construction or later to extend the service life during subsequent repairs or renovations— depending on the project’s specific requirements.
Injection can often be performed without extensive excavation or demolition, making it a less disruptive solution for existing structures or ground. This approach avoids the expensive costs associated with structural repairs and reduces operational downtime.
High-quality injection materials can provide long-lasting waterproofing protection, enhancing the lifespan of the structure.
Main Considerations for a Successful Injection Solution
Assess:
- The source of the water ingress
- The conditions of the structure
- Site conditions
- Target
Specify:
- The right problem-solving strategy
- The right products/ systems
Apply:
- The right application methods and skills
- The right application equipment
- Quality control
The success of injection depends on the combination of the right material specification, the appropriate injection equipment, and correct on-site application.
How are Injections Applied
Here is an example of how waterproofing injections in steel-reinforced concrete are done in four steps.
This step-by-step procedure demonstrates how to reach the defective area and helps avoid mistakes.
1. Drill
Drill into the substrate, crossing the crack at its midpoint.
2. Install packer
Install a packer (a pressure-tight connection from the pump through the drill-hole to the crack).
3. Activate and load material
Activate the injection material and load it into the pump.
4. Inject and fill
Start pumping, injecting, and filling the crack.
Watch a Video to See How Sika Injection 107 is Applied
Author
Matthias Ohnesorge
Corporate Product Engineer
Target Market Waterproofing
Sika Services AG
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