Why Do They Use Concrete for Highways?

People wonder, for good reason, why many of Colorado’s highways are still made using concrete, whereas practically all other roads are made of asphalt. Asphalt is less expensive, more flexible, and easier to maintain, so why would construction companies and local authorities opt for concrete instead? The answer is, unfortunately, not as straightforward as you might hope; several factors contribute to the different choices of materials for highways and streets in the United States. 

Since 2010, our team of experts at the Asphalt Doctors has gained extensive experience working with Colorado roads - read on for our insight on why concrete is used for highways and how this may be changing. 

The Makeup of Concrete vs Asphalt 

Concrete driveways, parking lots, sidewalks, and roads are made up of aggregates, including rock, lime, or gravel mixed with cement, which acts as a binder. Concrete can be fully recyclable using natural materials. Asphalt roads are very similar except that instead of cement as a binder, asphalt is a semi-solid form of petroleum. 

Asphalt roads are semi-recyclable and have become incredibly popular due to their low cost to install and maintain compared to concrete. They are extremely quick to install and reseal, further reducing costs. Furthermore, the rough granulated texture of asphalt roads provides far greater traction and skid resistance than concrete roads; asphalt is also heat-absorbing, which can better defrost winter ice and frost, significantly reducing the hazards of a slippery road. On top of that, because of asphalt’s flexibility, damaged asphalt roads usually only require a quick patch compared to concrete, which often requires a full slab to be removed and replaced. 

The Benefit of Using Concrete for Roads

There are over 4 million miles of road in America and over 45,000 miles of road that compiles the Interstate Highway System. The United States government began building the Interstate Highway System in the 1950s, and their primary standards were that the road would A) provide a long service life and B) provide safe travel. Both concrete and asphalt were in use at this time, but concrete was predominantly chosen due to the first standard - that these highways would offer a long service life. 

The main benefit of concrete is that it has a very long lifetime. Concrete roads can last up to 40 years before needing to be resealed, are naturally resistant to oil leaks, and are far less likely to develop potholes than asphalt. Asphalt, on the other hand, is usually resealed within 14 years and is less durable. Concrete is what is referred to as a “rigid” pavement, whereas asphalt is referred to as a “flexible” pavement - concrete has the advantage that it can withstand much heavier traffic for longer periods of time, and thus, it almost becomes obvious that concrete would be chosen even though it has a higher installation cost than asphalt. While less well-known, concrete can also be better for fuel consumption. Due to its reduced friction, vehicles may save between 1-14% on fuel when driving on concrete instead of asphalt. 

Why Not Concrete for All Roads? 

Concrete has historically been a popular highway choice, but this is not the case with roads across America more broadly. Only 30% of the Interstate Highway System still uses concrete today, and approximately 94% of urban roads use asphalt. Concrete lasts longer, so why is asphalt now the favored option? 

Probably the biggest reason for asphalt’s popularity is its low installation cost, coming in at around 40% less overall expense. In areas with harsh weather and temperature changes, concrete can be prone to cracking and often requires an expensive repair. Asphalt, on the other hand, is very inexpensive to repair comparatively. Asphalt can be laid and repaired faster and for less than concrete, making it an ideal choice when finances are a 10-20-year consideration. 

Asphalt is also a safer driving surface. As previously mentioned, asphalt roads have more excellent traction than concrete, making them less prone to hazardous freezing conditions - the same reason concrete is considered more fuel efficient: its slicker and less friction-inducing surface makes it less safe. While concrete roads can withstand heavier traffic over extended periods of time, asphalt is more flexible and better suited to accommodate frequent turns, stopping, and starting, a common feature of urban and residential areas. Finally, asphalt roads are known for reducing noise pollution due to their softer texture. According to a 2013 study by the World Road Association, asphalt roads were able to reduce sound by up to 7 decibels - a key advantage, once again, in urban and residential areas. 

In summary, concrete has been used for highways due to: 

  • Its longevity - up to 40 years of life
  • Its durability in heavy traffic 
  • Fuel efficiency
  • Pot-hole resistance

On the other hand, asphalt roads are being used more for highways and non-highway contexts due to: 

  • Relatively low installation cost
  • Low repair cost 
  • Quick repair time 
  • Safety 
  • Sound reduction 
  • Better suited for frequent stops, starts, and turning movements

Your Partner in Asphalt 

While we are indeed the Asphalt Doctors, our experienced professionals can deliver a solution to your roadway project using concrete or asphalt. Each paving material has advantages and disadvantages, but we’re here to serve you with a product that meets all standards of professionalism. Our experts are here to exceed your expectations through quality, ethics, and service. 
If you or someone you know is searching for a new roadway surface or repairs to an existing one, contact the Asphalt Doctors today!