What's the long-term effect of UV on Ottawa asphalt driveways?

UV radiation is one of the primary causes of asphalt deterioration in Ottawa, breaking down the petroleum-based binder that holds the aggregate together and causing the surface to become brittle, gray, and prone to cracking within 5-7 years if left unprotected.

UV damage occurs through a process called oxidation, where ultraviolet rays from the sun penetrate the asphalt surface and chemically alter the asphalt binder. Fresh asphalt contains oils and resins that keep it flexible and black. As UV exposure continues, these compounds evaporate or break down, leaving behind a harder, more brittle material that loses its ability to flex with temperature changes and traffic loads.

In Ottawa's climate, UV damage is particularly problematic because it works in combination with our extreme freeze-thaw cycles. UV-damaged asphalt becomes rigid and loses its elasticity, making it unable to handle the expansion and contraction that occurs when temperatures swing from -30°C in winter to +35°C in summer. This leads to surface cracking, which then allows water penetration and accelerates freeze-thaw damage. The combination of UV oxidation and freeze-thaw cycling can reduce an unsealed asphalt driveway's lifespan from 20-25 years down to 8-12 years.

Visual signs of UV damage include the asphalt surface turning from deep black to gray or brown, a chalky or dusty appearance, small aggregate particles becoming loose (called raveling), and the development of fine hairline cracks across the surface. Once UV damage reaches this stage, the asphalt binder has been compromised and water can penetrate more easily.

Sealcoating every 2-3 years is the most effective protection against UV damage in Ottawa. Quality asphalt emulsion sealers contain UV-blocking compounds that reflect sunlight and prevent it from reaching the asphalt binder below. A properly applied sealcoat can extend your driveway's lifespan by 5-10 years by maintaining the flexibility of the underlying asphalt. The ideal time for first sealcoating is 6-12 months after installation, once the asphalt has had time to cure and outgas volatile compounds.

When to Hire a Pro: While homeowners can apply sealcoat themselves, professional application ensures proper surface preparation, crack filling, and even coverage. Professionals use commercial-grade sealers and have the equipment to achieve uniform application. For driveways showing significant UV damage with widespread cracking and aggregate loss, consult a paving contractor about resurfacing rather than just sealing over deteriorated asphalt.

Need help finding a driveway contractor for sealcoating or resurfacing? Ottawa Driveways can match you with local paving professionals for a free estimate.