Whenever someone brings up the problems associated with premature tire wear, the first culprits mentioned are always alignment, inflation, or balance. Rarely does one think about the type of pavement trucks operate on.
It’s easy to say that doesn’t matter. After all, we can’t send trucks on routes based on how good the pavement is. A shame considering some surfaces are easier on tires than others.
Most of today’s Interstate Highway System is made of Portland Cement Concrete. The primary usage driver of this surface is durability. A PCC surface has a lifespan of around 25 years. That’s more than double the lifespan of asphalt surfaces.
PCC surfaces are also considered less susceptible to rutting, stresses, and issues with frost in colder climates. Heavy loads deliver a pounding to pavement, and PCC handles that pounding well.
That’s not to say asphalt has no advantages. First off, it’s less expensive in the short term. In the long term, it is believed lifecycle costs of both surfaces even out, depending on the price of oil, of course.
Asphalt is easier to repair and resurface, leading to less traffic disruption when it needs to be repaired. It is also more tolerant of bending stress and has a little more give over its lifetime.
A third type of pavement used may be even better than the first two: Asphalt-Rubber or Asphaltic Concrete Friction (AR-ACFC). In a twist of irony, AR-ACFC is made with chipped rubber from scrapped tires. It generally has better drainage characteristics, allows for quieter operation, and is less abrasive on tires.
The Tire Wear Emissions for Asphalt Rubber and Portland Cement Concrete Pavement Surfaces is a study that was conducted in 2005. It was designed to evaluate the efficacy of certain road surfaces.
The study found that AR-ACFC surfaces produced fewer rubber particles than a PCC surface. In simpler terms, this means AR-ACFC surfaces caused less tire wear than their counterparts.
This is important because it directly relates to public health. 1974 estimates put the average rubber loss at about 1.3 metric tons of rubber a year for the entire United States.
Of course, a lot has changes since that time, from tire durability to wear longevity, but there are still other considerations. If you take into account how many more vehicles are on the road today than there was 40 years ago, the problem is considerably worse.
Traction and Wear
The fact of the matter is we need traction on our roads. There are several design criteria for how rough the road should be to generate proper traction. The different types of pavement and multiple application techniques have direct impacts on how the tires wear.
In the end, it’s not just about concrete versus asphalt, or PCC versus AR-ACFC. It’s more about the texture of the road. There are two aspects of texture: the micro relates to the aggregate material itself, while the macro is geared toward water displacement. Both are necessary for traction.
Pavement engineers have historically focused on durability, traction and noise reduction. In the era of quiet cabs, noisy tires have no place. Even so, it usually is the tire industry alone focusing on wear.
What’s in Store?
The good news is people are focusing on this issue. The Pavements Group at the University of Illinois is working closely with the tire industry to determine what sorts of pavement optimizations are needed to create a better interface between the tire and the road.
Developing close relationships between industry and academia will yield better products, greater efficiencies and scalable materials. Ensuring the proper contact stresses means all industry players need to be involved.
There’s a lot that goes into the choice of pavements used for certain roads and surfaces. First and foremost is availability of materials, the experience of local contractors, and certain political pork-barrel considerations. How this will all play out in the future of trucking is anyone’s guess.