Concrete Bonding Agents – Types, Uses, and specifications
* Introduction
In construction, one common problem is that new concrete does not naturally bond with old concrete. To solve this, engineers use a Concrete Bonding Agent, which acts like glue and ensures strong adhesion between layers. This makes repairs, overlays, and extensions more durable.
* What is a Concrete Bonding Agent?
A bonding agent is a chemical (liquid or powder) used to make old concrete stick to new concrete.
Without it, the new concrete layer may peel off because concrete does not naturally bond well once it is hardened.
* Why Use a Bonding Agent?
- To repair damaged surfaces.
- For plastering and floor topping over old slabs.
- To avoid cracks or separation between old and new layers.
- To increase strength, durability, and waterproofing.
* How to Apply (Easy Steps)
- Clean the old surface – remove dust, grease, and loose particles.
- Apply the bonding agent with a brush, roller, or spray.
- Wait until tacky – don’t let it dry completely.
- Place the new concrete or mortar.
- Cure properly for long-lasting bonding.
* Tip: Think of it like Fevicol (glue) for concrete – without it, the new layer won’t stick properly.
* Types of Concrete Bonding Agents
1. PVA (Polyvinyl Acetate) Based
- Properties: Economical, water-based, good for plaster and small repairs, not suitable for wet areas.
- Specifications:
- Solid content: 40–50%
- Coverage: 4–6 m²/liter
- Drying time: 30–60 minutes
2. Acrylic / SBR (Styrene-Butadiene Rubber) Latex Based
- Properties: Strong, flexible, waterproof, reduces shrinkage, ideal for patching and flooring.
- Specifications:
- Solid content: 40–50%
- Coverage: 5–8 m²/liter
- Can be mixed into mortar/concrete for improved performance
3. Epoxy Based
- Properties: High bond strength, chemical and water resistant, used for RCC joints and structural repairs.
- Specifications:
- Two-component (resin + hardener)
- Coverage: 2–3 m²/kg
- Pot life: 30–45 minutes
- Compressive strength: >70 N/mm²
* Comparison Table
| Type | Bond Strength | Water Resistance | Cost | Best For |
|---|---|---|---|---|
| PVA | Low–Medium | Low | Affordable | Small repairs, plaster |
| Acrylic/SBR | Medium–High | Good | Moderate | Flooring, patching |
| Epoxy | Very High | Excellent | Expensive | Structural repairs |
* Conclusion
Choosing the right bonding agent depends on your project:
- PVA → for small, dry repairs.
- Acrylic/SBR → best all-rounder, waterproof and durable.
- Epoxy → for heavy-duty structural works.
With the right bonding agent, your old and new concrete layers bond strongly, ensuring long life and durability.
* FAQs on Concrete Bonding Agents
Q1: What is the main purpose of a concrete bonding agent?
Ans- To make old and new concrete surfaces bond strongly, preventing cracks and separation.
Q2: Which bonding agent is best for waterproofing?
Ans-Acrylic/SBR based agents are the best choice as they provide flexibility and water resistance.
Q3: Can I use PVA bonding agent for outdoor concrete repairs?
Ans-Not recommended – PVA is not durable in wet or external conditions.
Q4: Why is epoxy bonding agent expensive?
Ans- Because it provides very high strength and chemical resistance, making it suitable for structural works.
Q5: How do I choose the right bonding agent?
Ans- Select based on repair type: PVA for small repairs, Acrylic/SBR for general waterproof works, Epoxy for structural and heavy-duty applications.
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