Single Component Polyurethanes vs. Dual Component Polyurethanes

When it comes to polyurethane systems in geotechnical applications, choosing between single-component and dual-component products can significantly impact project outcomes. Each system offers unique advantages tailored to specific site conditions, performance requirements, and application techniques. As a leader in polyurethane innovation, NCFI Geotechnical is committed to helping professionals navigate these options with confidence. In this article, we’ll explore the key differences between single- and dual component polyurethanes, shedding light on their respective benefits and best-use scenarios, so you can make informed decisions for your next geotechnical challenge.

Single Component Polyurethanes

Single component polyurethanes are typically low viscosity, prepolymer products comprised of one main component. Reaction does not take place until the product comes into contact with moisture or water. Unlike dual component geotechnical polyurethane systems which are formulated for a specific reaction time, single component products can be catalyzed in the field to meet specific reaction times as soil conditions or applications dictate.

Key Facts About Single Component Polyurethanes:

These kinds of polyurethanes offer these key characteristics:

• Single component polyurethanes come in two main types: Hydrophobic or hydrophilic.
• Both offer different and unique physical properties that can be useful for various applications.

Single component polyurethanes come in two main types: Hydrophobic or hydrophilic. Both offer different properties that may be useful during different projects.

Hydrophobic: Polymerizes when exposed to moisture or water.

Hydrophilic: Can absorb up to 20x its volume in water, requires water to maintain structural integrity.

Typical Physical Properties and Use Characteristics:

• Low or Minimal Expansive Pressure
• Field adjustable Reaction Times
• Flexible or Rigid Foam Structure
• Formulated for long Term Repairs
• Low viscosity
• High Compression Strength when Measured in Sand

Ideal Applications of Single Component Polyurethanes

This formulation of geotechnical polyurethane foam is ideal for these applications:

Permeation Grouting: This process consists of pumping a predetermined amount of low viscosity single component directly into soils at depth allowing the product to permeate throughout the soil mass, flowing easily into fine soil particles, filling void spaces, and locking the soil mass together.

Dynamic Joint or Crack Sealing: Dynamic joints can be made up of two or more different materials, such as PVC pipe penetrations through a concrete wall. These low viscosity single components can bond to a variety of materials and substrates. Many of these products are flexible by design, making it ideal for accommodating the movement between different materials that make dynamic joints.

Non-Structural Long-Term Repairs: These single component products are extremely durable and offer high chemical resistance, ensuring a long-lasting repair.

Beyond these primary applications, single-component polyurethanes excel in a variety of specialized geotechnical and water-stop projects. Their adaptability and performance make them a strong solution for many different projects, such as:

• Basement Sealing and Water Stop
• Parking Garage Sealing
• Earthen Dam and Levee Sealing and Soil Stabilization
• Mine and Tunnel Applications
• Culvert Sealing
• Elevator Pit Crack Sealing
• Seawall and Bulkhead Repair
• Brick or Cast Manhole Sealing
• Utility Vault and Lift Station Sealing

While single component polyurethanes offer an ideal solution for many applications or projects, they are not ideal for every situation. These types of polyurethanes do not offer lifting or large volume void filling abilities. For projects requiring the precise lifting of structures or filling larger voids, dual-component polyurethanes are the preferred solution. These systems are specifically engineered to expand rapidly and with a controlled density, making them ideal for demanding geotechnical applications where lifting strength and stability are critical. Next, we’ll examine the unique properties and advantages of dual-component polyurethanes.

Dual Component Polyurethanes

Dual-component polyurethanes, as the name suggests, consist of two main components. These components are mixed at the time of application to trigger a chemical reaction that produces rapid expansion and curing. While some dual-component systems perform best in dry conditions, other formulations are designed to tolerate wet environments, making them versatile for applications requiring precise lifting, filling, or stabilization in a range of site conditions.

Key Facts About Dual Component Polyurethanes

Typical Physical Properties and Use Characteristics:

• High expansive pressure
• System specific speed
• Density tested per ASTM methods

Dual component polyurethanes come in two main types: hydrophobic and non-hydrophobic. Both offer different properties that may be useful for a variety of projects.

Hydrophobic: Can be used in saturated conditions
Non-Hydrophobic: Should not be used in saturated conditions

Ideal Applications of Dual Component Polyurethanes

This formulation of geotechnical polyurethane foam is ideal for these applications:

Deep Soil Injection: This method involves injecting polyurethane foam into a grid of injection points at varying depths underground, determined through geotechnical reports or field testing. Starting from shallow depths and progressing downward, foam is injected to fill voids, stabilize soil, and lift structures. Surface movement is monitored using tools like laser levels to ensure precision. This technique provides targeted stabilization and lifting, ideal for addressing deep subsurface weaknesses.

Long-Term Repairs: Dual-component polyurethanes are engineered for applications requiring high strength and precision, making them ideal for structural repairs. These formulations rapidly expand and cure to provide strong, stable support for lifting and stabilizing heavy loads. With precise mixing and controlled reactions, they create durable repairs that can withstand significant structural demands, even in challenging geotechnical conditions.

Dual component polyurethane can be used in a variety of specialized geotechnical applications, such as:

• Commercial, Residential, and Industrial Foundation Lifting
• Roadway Lifting and Leveling
• Bridge Transition Slab Realignment
• Seawall Repair
• Culvert Stabilization
• Manhole Rehabilitation
• Pipe Joint Sealing
• Parking Lot Leveling
• Driveway Leveling
• Concrete Slab Lifting and Leveling (also known as Slab Jacking)
• Rocking Concrete Slab Stabilization
• Dam and Levee Sealing and Stabilization
• Trip Hazard Repair

While dual-component polyurethanes offer lifting capabilities and some are formulated with hydrophobic properties, they are not always the ideal solution for every project. Choosing the right polyurethane system requires an understanding of site conditions, project goals, and the specific properties of the available formulations.

If you’re unsure which polyurethane formula is best for your upcoming project, the NCFI Geotechnical Polyurethanes team is here to help. Our experts bring extensive knowledge of polyurethane systems and their applications, ensuring you get the best solution for your geotechnical needs. We’re dedicated to helping you navigate your options and find the ideal solution to meet your goals. Contact us today to discuss your project’s needs.