Asphalt crack

Types of asphalt cracks

Asphalt cracks are the splits or fractures that develop on asphalt surfaces over time due to various factors.

• Hairline cracks: Hairline asphalt cracks are thin fissures that are challenging to notice. They usually begin to form in the summer due to high heat. If the weather gets colder, the hairline cracks might get bigger.
• Alligator cracks: They get their name because they look like alligator skin. Alligator cracks start small and get bigger over time. They might also develop a shallow and wide crack. Alligator cracks show that an asphalt surface is under stress or there is heavy traffic. Another reason might be the failure of the base or subgrade support.
• Diagonal cracks: Diagonal cracks form on an angle rather than in a straight line. They might develop near joints between two asphalt sections or along the edges. Diagonal cracks indicate that the asphalt material is shifting, settling, or expanding in different directions.
• Linear cracks: Linear cracks are straight fissures that run parallel to the asphalt edges. They are often long and narrow. Linear cracks might form naturally due to temperature changes or underlying material movement.
• Fatigue cracks: Fatigue cracks are thin cracks that often fan out and get bigger over time. They usually start at the center and move to the outer edge in a circular form. Fatigue cracks might be caused by repetitive bending and stretching of the asphalt material.
• Block cracks: Block cracks look like a series of interconnected squares or rectangles. They form when the asphalt material shrinks or settles unevenly. Unlike other cracks, block cracks can penetrate deep into the asphalt surface.
• Transverse cracks: Transverse cracks run perpendicular to asphalt paving and parallel to one another. They might develop when temperature changes cause the asphalt material to expand and contract. Transverse cracks can sometimes be shallow, long, and wide.

Proper identification of asphalt cracks can help determine the kind of crack filler for asphalt that should be used.

Specifications and maintenance of asphalt cracks

Specifications

• Chemical composition

  The ingredients for asphalt crack filler vary among products. Some include small flexible stones, sometimes called aggregate, and others include fibers or rubber.
  Besides the sealant ingredient, the filler will include solvents to make the consistency of the product smoother. When applied to the crack, it needs to penetrate deep within the fracture.
  Once cured, the solvents will have completely evaporated, and the product will be solid.

• Temperature requirements

  Many asphalt crack fillers need to be applied at a particular temperature, both for outside temperature and for the temperature of the filler itself. The material needs to be warm enough to flow into the cracks. Sometimes warming the material requires a heated truck or a kettle.

• Humidity

  Some fillers can be used in humid conditions but others should only be used when humidity is below a certain level.

• Filler sizes

  Asphalt cracks can come in various shapes and sizes, and different products are available to repair them. For small cracks (up to 1/2 inch wide), liquid sealants or crack sealant products are typically used. For larger gaps, a stronger material such as an asphalt rubber or hot pour should be utilized. Large gaps should also be filled with backer rod before using a sealant on the surface.

Maintenance

For asphalt crack sealing to be successful, careful surface preparation is key. Both the filler's surface and the area to be filled must be cleaned. Usually, hot air compressors, hand brooms, and blowers are sufficient for this task. In some instances, extra surface preparation may be required through the use of solvents, wire brushes, or propane torches.

The areas to be filled must be larger at the bottom than at the top to create a funnel-like structure. This is important because if the top of the crack is larger than the bottom, water could enter the crack through the funnel-like opening, and the seal would be unable to prevent it from penetrating.

Ensure that all debris, loose asphalt, and dirt has been removed before applying the sealing material. Initiating the sealing process after cleaning is essential because if water is present on the surface of the pavement or in the crack, the cracking material may not adhere. Filling should occur after at least 48 hours of dry weather.

Choose the right asphalt sealant crack filler for the task at hand, and ensure that it is applied to all cracks up to and including 1/4." Larger cracks will require additional preparation with backer rods or foam before filling.

Before applying crack sealing material to the asphalt, ensure no other sealing is required on the surface, as this could impact the sealing of the cracks.

For asphalt crack sealing to be successful, the proper product must be used to ensure it is compatible with the substrate and the crack being filled.

Industry applications of Asphalt cracks

• Preventive maintenance

  Asphalt crack filling serves as a proactive preventative maintenance approach to preserve asphalt surfaces. By sealing small cracks before they widen, further deterioration due to water intrusion, freeze-thaw cycles, and traffic stress is prevented. This extends the functional lifespan of paved areas while reducing long-term maintenance costs.

• Aged asphalt rejuvenation

  Even well-constructed asphalt will eventually show signs of aging. Crack filling not only stops damage but can also restore flexibility and longevity to surfaces that have grown rigid over time. Filling cracks with rejuvenating materials allows asphalt to regain some original properties, delaying the need for expensive full replacement.

• High-traffic surface protection

  Crack sealing proves essential in bus terminals, airport runways, freight facilities, and parking lot transit hubs. Preventing small flaws from becoming large failures helps maintain structural integrity under concentrated loading from heavy vehicles. This enhances safety by reducing the likelihood of pavement collapse or potholes forming.

• Cost savings through early intervention

  Investing in asphalt crack filler pays dividends financially. By addressing minor issues soon after pavement placement, agencies and property owners avoid costly patching, deep repair, or complete resurfacing later. It also minimizes expenses related to invasive repair methods that disturb underlying layers. Regular sealing of cracks using filler material allows funds to be directed toward other vital maintenance activities.

• Major infrastructure sustainability

  Transportation systems depend on sustainable practices that protect public assets while minimizing taxpayer burdens. Focusing resources on preserving existing asphalt through crack sealing makes economic and environmental sense. It reduces the need for virgin asphalt binder and aggregate to be mined, processed, and transport further reducing carbon emissions linked to roadway construction activities.

• Functional enhancement of surfaces

  Sealing joints and fissures improves not just asphalt's structural performance but also surfaces' functional qualities. Filling cracks prevents incompletely paved areas from degrading further, such as pothole formation. Sealing additives also improve friction, skid resistance, and surface drainage. Crack sealing preserves the smoothness of riding quality, safety, and surface water conveyance.

How to Choose Asphalt Cracks Filler

When buying asphalt crack fillers for resale or use, it helps to know what to look for. There are many options, and most pavement sealants work differently. Here are some things to consider when buying asphalt crack fillers.

• Asphalt Mix

  When purchasing asphalt crack fillers, it's best to consider the product's mix. Emulsions are water-based mixes ideal for smaller cracks and cheaper options. Solvent-based fillers have more flexibility and durability but come at a higher cost. Technically called CSS-1, SS-1, or MS-1, they are faster to set and are applicable for larger surface areas. Hot-pour sealants work better for larger cracks, are tougher, and last longer, but they need heat to set. They are great for high-traffic areas and resistant to weather changes. They also last longer than cold-pour fillers.

• Material

  Crack fillers are made from different materials. Buyers should consider the primary material used in the crack filler. They include latex, rubberized asphalt, polyurethane, and others. Each material has unique benefits, so research them well before buying.

• Size of Filler

  Filler sizes vary depending on the type of crack and area needed to work on. The size of the bottle or container will also differ, ranging from small tubes to large buckets. Determine the type of crack and area to work on before buying.

• Environmental Impact

  The need for environmentally-friendly products grows daily. When buying crack fillers, consider the impact they will have on the environment. Select products that have low volatile organic compounds.

Q & A

Q: What rubber is used in crack sealing?

A: The type of rubber used in crack sealing is known as Styrene Butadiene Styrene (SBS). It is a thermoplastic elastomer that blends rubber and plastic. SBS has a high tensile strength and offers excellent elasticity and resilience, making it suitable for asphalt crack sealing. When heated, SBS becomes soft and can be mixed with other components to form a sealant. Once cooled, it regains its rubbery strength and flexibility, allowing it to expand and contract with the pavement.

Q: What equipment is used for asphalt crack sealing?

A: The main piece of equipment used for asphalt crack sealing is a crack sealing kettle. It is a portable stovepipe or tank with an indirect flame heating system that heats up the sealant material. The kettle is usually mounted on a trailer or can be hand-held, and it will have hoses and nozzles to route the sealant where it is needed. Other tools used in conjunction with the kettle include wire brushes to clean the cracks, air compressors to remove debris from cracks, and router/explorers to create a uniform crack width.

Q: What are the different types of asphalt crack sealers?

A: The main types of asphalt crack sealers are rubberized hot pour sealants, cold pour sealants, and silicone sealant. Hot pour sealants are heated and poured into cracks, where they cool and harden. Cold pour sealants do not require heating and are applied directly to the crack. Cold pour sealants are easier to apply but less effective than hot pour. Silicone sealants are flexible and resistant to moisture, but they are more expensive and must be reapplied every 10 years.