Atrophy is a way of life in road and driveway pavement, but preventive maintenance can slow the process considerably.
Pavement is a lot like the cars that drive on it: From the first day onward, it depreciates.
Not that pavement, asphalt to be specific, doesn’t enjoy a long life. A well-designed, well-built stretch of asphalt roadway can continue to perform for 35 or even more years. That is, if it is well maintained. It matters how experienced an asphalt paving company is that performs the initial asphalt construction as well as the maintenance.
But to understand what constitutes a deteriorated pavement, which can happen even just a few years after the initial construction, it helps to understand the factors that break down pavement. An obvious culprit is traffic and the weight of the vehicles plying the roadways. The more and heavier the vehicles, the more that roads are damaged. Another is weather: too much hot weather can make the liquid parts of asphalt to become pliable; in extraordinary heat waves in Texas, the pavement sometimes experiences heat explosions as water trapped under pavement builds up into steam.
A subset of weather is what happens when water can percolate down through pavement cracks. That moisture gets into the sub-pavement, which can either wash away supporting gravel or, when frozen, expand the cavity and allow in even more water. As that freezes and thaws again, the pavement above will collapse into a pothole.
Ultraviolet rays from the sun also damage “blacktop” pavement. That sunlight leads to surface oxidation, which diminishes the oily resinous faction (bitumen) of the hydrocarbon chain. This increases the viscosity and decreases the ductility of the pavement, allowing the pressure of vehicles to pull it apart and make the surface a little more brittle. This is when cracks form on the surface – the fissures that allow the moisture in and below the surface of the road, parking lot or driveway.
As with cars, regular maintenance can at least stave off the inevitable and extend the life of the pavement. The good news, according to the National Asphalt Pavement Association, is that lifecycle costs of hot-mix asphalt are “significantly lower than those of Portland cement concrete pavements.” The NAPA bases this analysis from the recommendations for maintenance prescribed by the U.S. Federal Highway Administration. This is among the reasons why concrete highways are rare.
One paving company breaks down the ideal life-cycle maintenance schedule into years. While the variables of traffic loads – how much and how heavy – and weather affect this, the rules of thumb are as follows:
- Years 0-5: Very little maintenance required.
- Years 5-7: Begin preventive steps such as sealcoating and crack sealing.
- Years 7-15: Make minor repairs along with ongoing maintenance. This may include patch repairs (tricky in winter climates; often a temporary repair is made and a permanent repair is made later in dryer, warmer months), crack seals and additional sealcoating.
- Years 15-25: Major repairs are usually made in this phase, which can include more sealcoating, asphalt overlays or at least extensive patch repairs.
- Years 25-35: In this phase rational decisions have to be made about continued repairs or complete replacement.
Important to know about the latter stages: A sufficient number of external factors may have changed since the road or driveway was first constructed. That could include rerouting or new businesses requiring different traffic patterns, etc. These might be the ultimate determining factor in what happens. But suffice it to say that preventive maintenance in the earlier phases will keep the pavement intact far longer than if it were neglected.