In construction and structural repair, achieving a strong bond between old and new concrete is critical. Without a reliable bonding agent, the interface between layers can become a weak point, leading to cracking, delamination, and structural failure over time.
This is where epoxy bonding agents play an essential role. One of the most trusted solutions used by engineers and contractors worldwide is Sikadur®‑32 LP, a high-performance epoxy bonding agent designed for structural concrete applications.
In this comprehensive guide, we will explore what Sikadur®-32 LP is, its benefits, and how to properly apply it for maximum structural performance.
What is Sikadur®-32 LP?
Sikadur®‑32 LP is a two-component, solvent-free epoxy adhesive designed to create a strong bond between existing hardened concrete and newly placed concrete or mortar.
The product is manufactured by Sika AG, a global leader in construction chemicals and engineering solutions.
This bonding agent is commonly used in structural repairs, concrete extensions, and renovation projects, ensuring that new materials adhere firmly to existing surfaces.
Key Benefits of Sikadur®-32 LP
Using Sikadur®‑32 LP provides several advantages for structural concrete work.
1. Exceptional Bond Strength
The epoxy creates a chemical bond between old and new concrete, significantly stronger than mechanical bonding alone.
2. Structural Durability
Once cured, the bond resists:
- Heavy loads
- Water penetration
- Chemical exposure
- Mechanical stress
3. Moisture Tolerance
Unlike many bonding agents, Sikadur®-32 LP can be applied on slightly damp concrete surfaces, making it practical for repair work.
4. Easy Application
It can be applied using brushes, rollers, or spatulas, allowing contractors to work efficiently on various surfaces.
5. Long Service Life
Epoxy bonding ensures long-term structural integrity, especially in demanding environments like bridges, industrial floors, and foundations.
Common Applications
Engineers and contractors use Sikadur®‑32 LP in many structural scenarios, including:
Structural Concrete Repairs
Bonding new repair mortar to damaged concrete.
Concrete Extensions
Joining newly poured concrete slabs to existing structures.
Bridge and Infrastructure Repairs
Ensuring durable bonding in high-load environments.
Precast Concrete Connections
Strengthening joints between precast components.
Structural Mortar Bonding
Improving adhesion between mortar layers and concrete substrates.
Tools and Materials Needed
Before starting, prepare the following:
- Sikadur®‑32 LP (Component A & B)
- Clean mixing container
- Electric mixer or mixing paddle
- Brush, roller, or trowel
- Protective gloves and safety gear
- Concrete repair mortar or fresh concrete
Proper preparation ensures the bonding agent performs effectively.
Step-by-Step Guide: How to Use Sikadur®-32 LP
1. Prepare the Concrete Surface
Surface preparation is the most important step.
The surface must be:
- Clean
- Free of dust
- Free of grease or oil
- Free of loose particles
Recommended methods include:
- Wire brushing
- Sandblasting
- Grinding
The goal is to expose sound concrete for proper bonding.
2. Ensure Proper Surface Condition
Before applying the epoxy:
- The concrete should be slightly damp but not wet
- Remove standing water
- Allow surface pores to remain open
This improves adhesion.
3. Mix the Two Components
Sikadur®‑32 LP comes as two components:
- Component A (Resin)
- Component B (Hardener)
Mixing Process
- Pour Component B into Component A.
- Mix thoroughly using a slow-speed electric mixer.
- Continue mixing for at least 3 minutes until the mixture becomes uniform.
Proper mixing is essential for chemical curing and bonding strength.
4. Apply the Epoxy Bonding Agent
Once mixed, apply the epoxy to the prepared concrete surface using:
- A brush
- A roller
- A trowel
Ensure a thin, uniform layer across the entire surface.
Avoid excessive thickness.
5. Place the New Concrete or Mortar
After applying the bonding agent:
- Place the fresh concrete or repair mortar while the epoxy is still tacky.
This is known as the “wet-on-tacky” method, which ensures the strongest bond.
If the epoxy fully cures before placing concrete, bonding effectiveness may reduce.
6. Finish and Cure the Concrete
Once the new concrete is placed:
- Compact properly
- Finish the surface
- Follow standard curing procedures
Proper curing improves overall durability.
Technical Performance Characteristics
Sikadur®‑32 LP offers several high-performance properties:
- High compressive strength
- Excellent adhesion to concrete and steel
- Low shrinkage
- Chemical resistance
- Waterproof bonding interface
These characteristics make it suitable for structural and heavy-duty applications.
Best Practices for Successful Application
To achieve optimal results:
✔ Always prepare the surface properly
✔ Mix components thoroughly
✔ Apply evenly without gaps
✔ Place new concrete before epoxy fully cures
✔ Work within the product’s recommended pot life
Following these steps ensures maximum bonding performance.
Common Mistakes to Avoid
Even experienced contractors can make mistakes when using epoxy bonding agents.
Avoid these common issues:
Poor Surface Preparation
Dust or loose particles weaken the bond.
Incorrect Mixing Ratio
Always mix full kits or correct proportions.
Delayed Concrete Placement
Placing concrete after epoxy cures can reduce bonding strength.
Applying on Wet Surfaces
Standing water prevents proper adhesion.
Why Professionals Trust Sikadur®-32 LP
Products from Sika AG are trusted worldwide for structural engineering and repair.
Contractors prefer Sikadur®‑32 LP because it provides:
- Reliable structural bonding
- Long-term durability
- Easy application
- High mechanical performance
From infrastructure repairs to residential construction, it is one of the most dependable epoxy bonding solutions available.
Final Thoughts
When bonding new concrete to existing structures, using a high-quality epoxy bonding agent is essential for structural integrity. Sikadur®‑32 LP provides a powerful solution that ensures strong adhesion, durability, and long-lasting performance.
By following proper surface preparation, mixing, and application techniques, contractors can achieve professional-grade results and significantly extend the life of concrete structures.
For engineers, builders, and repair specialists, Sikadur®-32 LP remains a trusted solution for structural concrete bonding worldwide.
