ARDEX K 15 is one of the most widely specified self-leveling underlayments in North America, known for its versatility and speed in preparing surfaces for finished flooring. This article provides a comprehensive overview of its installation process, including substrate preparation, mixing procedures, application techniques, and performance specifications. The information is derived exclusively from official product documentation and manufacturer guidance.
Overview of ARDEX K 15
ARDEX K 15 is a Portland cement-based self-leveling underlayment formulated with a special blend of polymers. It is designed for interior use and can be applied on, above, or below grade. The product is ideal for leveling and smoothing surfaces such as concrete, terrazzo, ceramic and quarry tile, epoxy coating systems, wood, metal, and non-water soluble adhesive residue on concrete. It is also suitable for use over concrete treated with certain curing compounds.
Key features include: - Rapid setting and quick walkability - Pourable or pumpable when mixed with water - Capable of being installed in thicknesses ranging from 1/8” to 1.5” neat, or up to 5” with aggregate - Can be tapered to meet existing elevations - Compressive strength of 5,500 psi and flexural strength of 1,200 psi
Substrate Preparation
Before applying ARDEX K 15, the substrate must be properly prepared to ensure optimal adhesion and performance. The following steps should be followed:
1. Surface Inspection
- Ensure the substrate is clean, sound, and free from contaminants such as oil, grease, or loose material.
- Check for any irregularities or depressions that need to be filled or corrected.
2. Priming
- Concrete Substrates: Use ARDEX P 51™ Primer.
- Most Non-Porous Substrates, Epoxy Coatings, and Adhesive Residue: Use ARDEX P 82™ Ultra Prime.
- Apply the primer according to the manufacturer's instructions, ensuring even coverage.
3. Mechanical Profiling
- Mechanical profiling is not required for most applications, but may be necessary for certain substrates to enhance adhesion.
Mixing and Application
ARDEX K 15 is mixed with water and must be applied within its flow time, which is approximately 10 minutes. The following steps outline the mixing and application process:
1. Mixing
- Use clean, potable water for mixing.
- Add the contents of one 55 lb (25 kg) bag to the water in a mixing container.
- Use a low-speed electric drill with a mixing paddle to thoroughly blend the mixture until it is smooth and free of lumps.
- Do not overmix, as this can affect the product's performance.
2. Pouring and Pumping
- ARDEX K 15 can be poured or pumped using the ROVER® or AMP® system.
- Ensure the area to be covered is free of debris and properly primed.
- Pour the mixture into the center of the area and allow it to flow outward, leveling itself naturally.
3. Thickness Application
- ARDEX K 15 can be applied neat (without aggregate) at thicknesses ranging from 1/8” to 1.5”.
- For thicker applications, aggregate can be added to increase the coverage and structural support.
- The product can also be tapered to meet existing elevations, making it suitable for sloped or uneven surfaces.
Performance and Curing
ARDEX K 15 has a rapid setting time, making it ideal for projects with tight deadlines. The following are key performance and curing times:
- Flow Time: 10 minutes
- Initial Set (ASTM C191): Approximately 30 minutes
- Final Set (ASTM C191): Approximately 90 minutes
- Walkable: 2 to 3 hours
- Floor Covering Installation:
- Moisture-insensitive tile and stone: 6 hours
- All other floor coverings: 16 hours
These times may vary depending on ambient temperature and humidity. It is recommended to allow for additional time in cooler or more humid conditions.
Compatibility and Use Cases
ARDEX K 15 is suitable for a wide range of substrates and applications. It is recommended for both residential and commercial settings, including:
- Concrete floors
- Terrazzo surfaces
- Ceramic and quarry tile
- Epoxy coating systems
- Wood and metal substrates
- Non-water soluble adhesive residue on concrete
It is also compatible with certain curing compounds, but users should consult the manufacturer's documentation for specific compatibility information.
Comparison with Other ARDEX Products
While ARDEX K 15 is a versatile and high-performance product, it is important to understand how it compares to other ARDEX underlayments to ensure the best fit for a given project.
ARDEX K 10 – The Reactivatable Solution
- Applications: High-flow formula suitable for multiple pours.
- Features: Self-levels up to 1 inch, with floor coverings ready in 16 hours.
- Strength: Compressive strength of 4,200 psi, flexural strength of 1,000 psi.
- Healing Time: Extended flow time of up to 25 minutes, ideal for large or complex pours.
ARDEX K 16 – High-Flow Self-Leveling Underlayment
- Applications: Smoothing interior concrete, terrazzo, ceramic and quarry tile, epoxy coating systems, and non-water soluble adhesive residue.
- Features: Pours like water, can be installed at 1/8” thickness.
- Strength: High durability with microfiber reinforcement.
- Installation Time: Floor coverings can be installed in 16 hours.
ARDEX K 55 MICROTEC – Thin Application Specialist
- Applications: Ideal for thin applications over large areas.
- Features: High-flow technology, remains fluid even at 1/8” thickness.
- Installation Range: Can be installed from 1/16” to 1” neat.
- Strength: Suitable for both interior and exterior applications.
ARDEX K 55 RAPID – Fast-Setting Solution
- Applications: Durable and fast-drying, suitable for quick turnaround projects.
- Features: Can receive floor covering in as little as 2 hours.
- Strength: High compressive and flexural strength.
Each product has its own set of advantages and limitations, and the choice depends on the specific requirements of the project, including substrate type, desired thickness, and time constraints.
Best Practices and Safety Considerations
To ensure a successful installation of ARDEX K 15, it is important to follow best practices and safety guidelines:
1. Environmental Conditions
- Install the product in a controlled environment with stable temperature and humidity levels.
- Avoid installation in extreme temperatures or high humidity, as this can affect setting times and performance.
2. Personal Protective Equipment (PPE)
- Wear appropriate PPE, including gloves, safety goggles, and a dust mask, to protect against skin and eye irritation.
- Follow all safety guidelines provided by the manufacturer.
3. Storage and Handling
- Store ARDEX K 15 in a dry, cool place away from direct sunlight.
- Keep the product in its original packaging until ready for use to prevent moisture absorption.
4. Cleanup
- Clean tools and equipment immediately after use with water.
- Dispose of any unused material according to local regulations.
Troubleshooting Common Issues
Despite its high quality and reliability, users may encounter certain issues during the installation of ARDEX K 15. The following are common problems and potential solutions:
1. Lumps or Inconsistent Mixing
- Cause: Improper mixing or using contaminated water.
- Solution: Ensure the product is mixed thoroughly using clean, potable water. If lumps are present, discard the batch and prepare a new one.
2. Uneven Surface After Application
- Cause: Incorrect flow or improper pouring technique.
- Solution: Ensure the area is properly primed and free of debris. Pour the mixture into the center and allow it to flow outward naturally. Avoid disturbing the surface during the flow time.
3. Delayed Setting Time
- Cause: Cold or humid conditions, or incorrect water-to-powder ratio.
- Solution: Adjust the ambient temperature and humidity if possible. Ensure the correct water-to-powder ratio is used during mixing.
4. Cracking or Shrinkage
- Cause: Insufficient curing time or improper surface preparation.
- Solution: Allow the product to cure fully before installing floor coverings. Ensure the surface is clean, sound, and properly primed before application.
Conclusion
ARDEX K 15 is a highly versatile and fast-setting self-leveling underlayment suitable for a wide range of substrates and applications. Its high compressive strength, rapid setting time, and ease of application make it a preferred choice for both residential and commercial flooring projects. By following proper installation procedures, surface preparation, and safety guidelines, users can achieve a smooth, durable, and level surface ready for finished flooring. The product's compatibility with various substrates and its ability to be applied in varying thicknesses further enhance its utility in diverse construction scenarios.