Cracks in asphalt pavement allow water to penetrate the sub-base layer beneath the surface. When moisture seeps into the foundation, it weakens the pavement’s structural integrity, leading to accelerated deterioration and potholes. This damage is compounded by the freeze-thaw cycle, where trapped water expands and forces the crack to widen. Addressing these fissures promptly prevents foundation erosion and extends the lifespan of the paved area. Selecting the correct filler material and application method is crucial for an effective solution.
The Main Types of Asphalt Crack Fillers
The market for asphalt repair materials is primarily divided into two categories: cold pour and hot pour fillers. Cold pour crack fillers are typically asphalt emulsions or polymer-based liquids that are ready to use directly from a bottle or cartridge, making them the most accessible option for do-it-yourself projects. These materials are designed for ease of application and are generally suitable for smaller, non-moving cracks, offering a lifespan of approximately one to two years before reapplication is needed.
Hot pour fillers are a professional-grade solution composed of polymer-modified rubberized asphalt. This material is delivered in solid form and must be heated to around 400°F using specialized equipment before application. The heating process allows the compound to achieve low viscosity, enabling it to flow deeply into the crack and form a strong, flexible bond. This superior flexibility allows the filler to expand and contract with the pavement during temperature fluctuations, offering greater durability, often lasting between five and ten years. A third category includes specialty mastics, which are thicker, aggregate-filled compounds used for repairing very large voids or extensive, interconnected cracking.
Choosing the Right Filler Based on Crack Size and Type
The decision of which filler to use hinges almost entirely on the width and nature of the crack being repaired. For hairline cracks up to about 1/4 inch wide, a cold pour liquid filler is generally sufficient to seal the surface and prevent water intrusion. These smaller cracks do not experience the same degree of movement as larger ones, so the lower flexibility of the cold pour material is less of a concern.
Cracks ranging from 1/4 inch up to one inch wide require a material with greater elasticity to accommodate the pavement’s natural expansion and contraction. For this size range, the rubberized hot pour filler is the recommended choice due to its ability to maintain adhesion and flexibility across wide temperature swings. Using a less flexible cold pour product on these wider cracks often results in the material becoming brittle and being ejected from the crack during the first freeze-thaw cycle.
It is important to distinguish between simple linear cracks and a pattern known as “alligator cracking,” which resembles the skin of an alligator. Alligator cracking indicates a failure of the sub-base layer beneath the asphalt, often caused by water saturation or inadequate support. Simple crack filling will not resolve this underlying structural issue, and these areas typically require a more extensive repair, such as a full-depth patch or the application of a specialized mastic compound.
Step-by-Step Guide to Proper Application
Successful crack repair relies on meticulous preparation, as the filler must bond directly to clean, dry asphalt. The first step involves thoroughly cleaning the crack to remove all loose debris, dirt, vegetation, and moisture. Use a wire brush or specialized tool to scrape the walls, followed by a leaf blower or compressed air to ensure the crack is completely dust-free.
The crack must be completely dry before application, as moisture will prevent proper adhesion and compromise the filler’s performance. For cracks deeper than one inch, it is advisable to insert a backer rod or use sand to partially fill the void, ensuring the filler material is not excessively deep. This depth management prevents unnecessary material usage and ensures the filler cures uniformly, maintaining its intended flexibility.
When applying cold pour material, the liquid should be squeezed into the crack, slightly overfilling it to account for settling. The excess material is then smoothed flush with the pavement surface using a squeegee or trowel. Hot pour material is applied using a specialized melter-applicator, which dispenses the molten rubberized compound directly into the crack, often leaving a slight overband on the surface to maximize the seal. The repaired area must be protected from traffic for the manufacturer’s specified curing time, typically between 24 and 48 hours.
Maximizing Repair Longevity
The final step in a comprehensive asphalt maintenance plan is the application of a sealcoat over the entire pavement surface. Sealcoating is a protective layer that shields the asphalt from the damaging effects of ultraviolet (UV) radiation, oil spills, and water penetration. Applying a sealcoat over the filled cracks, once the filler has fully cured, significantly extends the life of the repair by protecting the exposed material from weathering.
This protective coating helps to lock the filler in place and provides a uniform appearance across the pavement. Property owners should plan for annual inspections of the repaired areas to check for any new fissures or signs that the existing filler is beginning to fail. Promptly addressing any re-opened cracks with a small amount of fresh material prevents minor issues from escalating into major structural problems.