ForConstructionPros.com

By Jeff Lax

When it comes to old, worn asphalt driveways and parking lots, commercial real estate owners, property managers, and even owners of single-family homes struggle with the same questions: Do we repave or sealcoat after making repairs to cracks, potholes and depressions? What is the most cost-effective and durable solution?

The industry has debated this issue for decades, and what has been learned is that each option has lasting, dramatic effects and that they actually complement one another. That’s the information pavement maintenance contractors need to convey to their clients who are trying to decide which pavement maintenance option best suits their needs and property.

Sealing

Sealcoating is one of the most important steps to protecting an owner’s investment in an asphalt driveway or parking lot. Sealers consist of emulsions that combine asphalt or refined coal tar with clays, mineral fillers, and water. Once applied, the water evaporates and the emulsion hardens to form a protective coating. It also becomes a beautiful black surface that adds curb appeal, giving a single-family home, multi-family residence, or commercial or industrial property a polished look. Industry experts agree that driveways or parking lots lacking the sealer can generally last only five to six years before the beginning stages of breakdown.

Initial sealing should occur six to 12 months after the asphalt surface is laid to allow the pavement to “cure” so oils can escape and the surface becomes ready for sealer. The initial sealer application forms a barrier to prevent water penetration and to inhibit deterioration of the asphalt binder by oxidation and over-drying.

As unprotected pavement ages the asphalt binder hardens, losing flexibility and becoming increasingly brittle. Ultraviolet rays from the sun break down the carbon bonds in asphalt, further weakening the pavement. Also, daily and seasonal cycles of heating and cooling cause the pavement to expand and contract. These stresses eventually exceed the pavement’s ability to flex, and cracks form. If water seeps into the cracks and freezes, the cracks expand, allowing more water to penetrate, making the cracks wider and deeper. This cycle leads to accelerated deterioration of the parking lot surface. Early sealcoating can prevent all these preliminary dangers to the life of the asphalt.