Asphalt vs Concrete roads

When it comes to the construction of roads or highways, choosing the right type of road material and the construction process needs some critical considerations. Of the two types of roads, asphalt and cement concrete roads, each type has merits and demerits, which are evaluated against some given criteria to reach a conclusion.

Budget is the primary consideration but not the final, as the concerned departments have to ensure the most value when deciding on a new road project. Therefore, it involves comparing the properties of both types and their sustainability factors against the expected climatic and traffic conditions.

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Asphalt vs. concrete – what are the differences?

Asphalt and concrete are both prominent road construction materials, although they have fundamental differences. Asphalt is a petroleum-based material that is flexible and can resist high temperatures. It is also easier and less costly to replace than concrete.  

Concrete, on the other hand, is a more durable road material that can last up to 30 years if properly maintained. It is also more environmentally friendly than asphalt. Understanding these distinctions will allow you to make an informed decision when selecting between the two materials for your project. Here are more on the differences between the two:

Composition

 Asphalt is composed of aggregates (sand, gravel, and crushed stone) and a petroleum-based binder. Concrete, on the other hand, is a mixture of aggregates, cement, and water.

Appearance 

Asphalt’s appearance is often black or dark brown, with a slightly rough, textured surface. Concrete, on the other hand, can be formed in a range of hues and textures, depending on the ingredients used in the combination.

Endurance

Although asphalt and concrete are both long-lasting materials, they have distinct strengths and weaknesses. Asphalt is more flexible and can sustain under high temperatures. However, asphalt is more vulnerable to damage from oil and petrol spills. Concrete roads do not develop dips and rutting like asphalt roads and they hold up better in comparison under heavy loads and pressure. Concrete also does much better than asphalt in freezing temperatures.

Construction procedure 

Asphalt is normally installed with a paving machine, which spreads the hot asphalt mixture over a prepared surface before compacting it to form a flat surface. Concrete, on the other hand, is poured over a prepared surface and then smoothed and leveled using mostly hand tools.

Maintenance

Both materials require routine maintenance to preserve their longevity. Asphalt should be sealed every few years to protect it from water and UV radiation. Concrete may need to be resealed every 5–10 years to keep its beauty and defend against stains and deterioration.

Why are Asphalt roads more common?

• Asphalt is less expensive to install, except during periods of petroleum price hikes. Only then are the costs of the two pavement types comparable.
• Asphalt is easier to repair. All municipalities and local bodies keep the necessary equipment to fix potholes in asphalt surfaces.
• Asphalt is simpler, faster, and less expensive to remove and rebuild in order to obtain access to services beneath the roadway.
• Asphalt pavement has advantages in snowy climates. As sunlight hits a ploughed roadway, it warms up and melts the snow left behind by the plough. Asphalt roads also withstand salt better than new concrete surfaces.
• Asphalt improves traction and skid resistance for cars.

But why is asphalt not used everywhere?

• Asphalt is prone to tearing and rutting on roadway segments with frequent turning and halting locations.
• Asphalt may fracture in extreme cold and rut in excessive heat if the incorrect oil is used in the asphalt mix. The end result is a road surface that is bound to elicit complaints from drivers.
• Asphalt has a shorter life expectancy than concrete, at around 18 years compared to 25 years. Although both surfaces can endure up to 40 years, asphalt requires more care.

What are the benefits of concrete?

• Concrete performs well under heavy traffic loads. If the road has to carry large interstate trucks with several tonnes of goods, it’s natural for the authorities to vote for concrete roads.

• Concrete typically requires fewer repairs, making it an ideal alternative for metropolitan streets with high traffic loads. Less maintenance equals fewer traffic delays and lower budget demands.

• Concrete can be stamped and/or painted to improve safety at crosswalks or to enhance the overall appeal of a location.

• Concrete road surfaces can endure up to 30 years, compared to 18 for asphalt. With good care, both surfaces can last up to 40 years, but concrete requires less maintenance.

But why is concrete not the default choice for road construction?

• Concrete roads are much more expensive than asphalt roads. The initial cost may be higher than local budgets can afford.
• Concrete can be noisier; the surface is roughened during building to improve tyre grip. Over time, the concrete slabs shift a little to settle, creating a rhythmic sound that many drivers find unpleasant.
• Concrete may become pockmarked in places with freeze-thaw cycles, especially if the locally available aggregate used in the concrete mix contains a high “chert” concentration. Chert is a type of rock that retains moisture. During freeze-thaw cycles, the chert swells and pops out of the pavement, producing holes that only worsen over time.
• Concrete, when new, can be harmed by salt used to reduce road ice. Some agencies choose a salt-free approach for the first one or two winters. That is a worry in locations with regular road icing.
• Concrete may be more expensive and difficult to repair. Instead of repairing a problem location, workers must normally remove a section of the road and replace it with new concrete. The same is true if there are utilities beneath the road that require replacement or maintenance. Removing the road surface and installing new material is more complex and costly than performing the same task on an asphalt road.

When debating on asphalt vs concrete for a road project, the major considerations that influence the selection are the initial cost of construction, the cost of upkeep and ultimate replacement, the location of subsurface utilities, and the kind and volume of traffic.

Asphalt is normally installed with a paving machine, which spreads the hot asphalt mixture over a prepared surface before compacting it to form a flat surface. Concrete, on the other hand, is poured over a prepared surface and then smoothed and levelled with hand tools.

Property	Asphalt Roads	Concrete Roads
Initial Cost	Lower	Higher
Maintenance	Requires regular sealing and occasional repairs	Fewer repairs, but may require complete replacement
Durability	Shorter lifespan (~18 years)	Longer lifespan (~30 years)
Environmental Impact	Petroleum-based, less eco-friendly	More environmentally friendly
Performance in Heat	Flexible, can withstand high temperatures	Can develop cracks in extreme heat
Performance in Cold	More prone to cracking	Better resistance to freeze-thaw cycles
Construction	Paved with a paving machine	Poured and leveled manually
Noise	Quieter	Can be noisier due to surface texture
Repair	Easier to repair potholes	More complex and costly repairs
Resistance to Oil/Salt	Susceptible to damage from oil and petrol spills	Better resistance to salt and chemicals

Conclusion:

The debate between asphalt and concrete roads boils down to a nuanced consideration of various factors such as initial cost, maintenance requirements, durability, environmental impact, and performance under specific conditions. Asphalt, with its lower initial cost and ease of repair, remains a popular choice for many road projects, particularly in areas with moderate climates and heavy traffic loads. Its flexibility and skid resistance makes it suitable for regions with frequent freeze-thaw cycles or where traction is crucial. However, concrete offers superior durability and longevity, making it a preferred option for high-traffic areas and locations where long-term maintenance costs are a concern. Concrete’s resistance to heavy loads and its ability to withstand extreme temperatures make it a reliable choice for highways and urban streets. Ultimately, the selection between asphalt and concrete roads depends on a careful evaluation of local conditions, budget constraints, and long-term objectives.