Sikaflex®-1c SL vs. Vulkem® 45SSL: Choosing the Right Self-Leveling Joint Sealant for Your Project
When it comes to sealing horizontal concrete joints, choosing the right sealant is just as important as choosing the right concrete mix. Whether you’re working on sidewalks, pool decks, warehouses, or plaza decks, a high-performance joint sealant protects your slab from water intrusion, debris, freeze–thaw damage, and long-term structural cracking.
Two of the most trusted options on today’s market are Sikaflex®-1c SL and Vulkem® 45SSL — both one-component, moisture-curing polyurethane sealants designed for horizontal expansion joints. While they share many similarities, each product has unique advantages that make it ideal for specific environments and job conditions.
Below, we break down what they are, how they work, and how to choose the best sealant for your application.
What Are Self-Leveling Polyurethane Joint Sealants?
Self-leveling polyurethane sealants are formulated to flow into horizontal joints and automatically level themselves without extensive tooling. Once cured, they remain flexible, durable, and weather-resistant. These materials are widely used in:
- Sidewalks & walkways
- Concrete slabs & pavements
- Patios, terraces, and balconies
- Parking lots
- Pool decks
- Warehouse floors
- Plazas and commercial entryways
The goal is simple: create a long-lasting elastic joint that allows for movement while keeping out water, chemicals, and debris.
Meet the Products
Sikaflex®-1c SL
A Fully Self-Leveling Polyurethane Sealant
Sikaflex®-1c SL is a premium-grade, one-component polyurethane designed to flow freely into horizontal joints. It cures quickly, resists aging and weathering, and can even be applied to "green" (24-hour old) or damp concrete under the right conditions.
Key Advantages
- Fully self-leveling — extremely easy application
- Tack-free in as little as 1–2 hours
- High elasticity and excellent adhesion
- Suitable for water immersion (with primer)
- Jet-fuel resistant
- Can be applied to damp or green concrete
- Ideal for sidewalks, plazas, pavements, and warehouse floors
Vulkem® 45SSL
A Semi-Self-Leveling, High-Movement Polyurethane Sealant
Vulkem 45SSL uses advanced polymer technology that gives it outstanding UV resistance, flexibility, and durability — particularly in high-traffic or high-movement environments. It is semi-self-leveling, which means it flows but maintains more shape than a fully self-leveling product.
Key Advantages
- ±35% movement capability (and up to +100/-50% modified)
- Performs exceptionally on sloped horizontal surfaces (up to 6%)
- Excellent adhesion to damp or green concrete
- High tensile strength and elongation
- Jet-fuel resistant
- Traffic-rated and extremely durable
- Suitable for continuous immersion in non-chlorinated water
Where Each Product Excels
Understanding the environment and joint conditions is the best way to choose between Sikaflex-1c SL and Vulkem 45SSL.
1. Project Slope and Surface Conditions
Choose Sikaflex®-1c SL if…
You’re sealing flat, level horizontal joints where a smooth, free-flowing pour is ideal.
Choose Vulkem® 45SSL if…
Your slab has a slope up to 6% — such as a pool deck, entry ramp, or patio.
The semi-self-leveling formula prevents run-off on angled surfaces.
2. Joint Movement
Movement capability matters in areas exposed to temperature swings or heavy loading.
- Sikaflex-1c SL: ±25%
- Vulkem 45SSL: ±35% (and +100/-50% modified)
Choose Vulkem® 45SSL for high-movement joints.
3. Water Exposure
Sikaflex®-1c SL
Suitable for chlorinated and non-chlorinated water, as long as priming and proper cure time are followed.
Vulkem® 45SSL
Safe for non-chlorinated water immersion only.
4. Cure Time and Application Speed
- Sikaflex: tack-free in 1–2 hours, faster surface cure
- Vulkem: skin in 2 hours, tack-free in around 5 hours
Choose Sikaflex®-1c SL for fast turnaround and minimal downtime.
Side-by-Side Comparison
| Feature | Sikaflex®-1c SL | Vulkem® 45SSL |
| Type | Fully self-leveling | Semi-self-leveling |
| Movement Capability | ±25% | ±35% (+100/-50% modified) |
| Slope Compatibility | Best on flat surfaces | Up to 6% slope |
| Tack-Free Time | 1–2 hours | ~5 hours |
| Water Immersion | Chlorinated & non-chlorinated (with primer) | Non-chlorinated only |
| Traffic Rating | Durable | Heavy traffic rated |
| Elongation | ~320% | 600–750% |
| Ideal For | Walkways, plazas, concrete slabs | High-movement, sloped, high-traffic areas |
Which One Should You Choose?
Choose Sikaflex®-1c SL if you need:
- A fully self-leveling, extremely easy-to-pour sealant
- Fast tack-free time
- Chlorinated water compatibility
- Reliable performance on flat slabs
Choose Vulkem® 45SSL if you need:
- A sealant for sloped slabs
- Maximum movement capability
- Superior traffic resistance
- Extremely high flexibility
Both sealants are professional-grade solutions, and the right choice mostly depends on your surface slope, expected joint movement, and environmental conditions.
Need Help Choosing?
At AWarehouseFull, we specialize in helping contractors, builders, and maintenance teams select the right materials for long-lasting concrete protection. If you’re unsure which product is right for your job, our team is always here to help.
Reach out to us anytime for technical guidance, quotes, or product recommendations.