Choosing the right paving material for your parking lot, driveway or patio project is a major decision. How do you determine whether concrete or asphalt is the better choice for your project? Beyond aesthetics (concrete allows many more options for decorative colors and patterns), multiple factors go into making the right decision. These include:
Concrete typically costs a bit more up front but has a longer life span and requires considerably less long-term maintenance and repair over its lifetime. In fact, while it may cost more at first, concrete can last more than twice as long as asphalt with significantly less maintenance and deterioration. Initially, asphalt may appear less expensive, but the frequent maintenance and replacement costs associated with asphalt pavement make it more expensive in the long-term. In addition, there are indirect costs—known as user delay costs—caused by reconstruction due to delay or inconvenience that are often not factored when doing a cost analysis.
The additional up-front costs of the concrete material itself and preparing the ground underneath the concrete can make a significant difference in the longevity of the material and the full life-cycle cost comparison between concrete and asphalt. In fact, independent studies show concrete pavements cost 50% less in ongoing maintenance than asphalt.
Just how long does concrete last? A concrete driveway or parking lot installed on a solid base with good drainage will last 40 or more years, more than double the average life span of asphalt. While the initial installation cost may be higher, over the lifetime of the product, the additional up-front costs make sense. When easier maintenance, decorative options and increased property value are factored in, concrete becomes the most cost-effective choice.
And concrete, when correctly installed and maintained, is a long-term solution that can increase the overall value of your property.
Most people understand that different materials will have different associated costs, but what about the time it takes to get the work done? For a business or resident who is impacted by the length of time it takes to rebuild a pavement, experiencing a long downtime can not only be problematic—it can be costly. When considering the type of material to use, the project’s duration should be measured, and the indirect cost of that downtime should be assessed.
Most asphalt driveways or parking lots require at least two applications to get the full thickness needed to support vehicle traffic. The base (or first) layer of asphalt is usually not strong enough to allow considerable amounts of traffic. Concrete is placed in one full layer which means that the duration of a concrete project can be as little as half the actual construction time as asphalt, resulting in less disruption and indirect costs to businesses, residents and drivers.
Pavement systems in areas like Michigan, where extreme temperature swings are the norm, can experience a reduced life expectancy. For example, when water seeps into cracks in the pavement and freezes, the result can be swelling and bending. When the ice thaws, the gaps below the surface are left unsupported and susceptible to the formation of potholes. Rock salt can further accelerate the damage.
A properly designed concrete mixture has the required durability and strength when it hardens and cures. Exterior concrete mixtures contain air content of five to eight percent which provides durability during the freeze-thaw cycle. In addition, because concrete is a rigid paving system, it will not warp or deform due to intense heat. Minnesota, a state that experiences even more extreme temperature swings than Michigan, has a new concrete pavement design expected to last more than 60 years with minimal maintenance. This expectation exceeds the already impressive findings of federally funded studies that show concrete interstate highways across the United States last about 2.5 times longer on average than asphalt highways.
What makes concrete so durable? Concrete is made of a mixture of aggregates, portland cement and water. It may also include supplemental cementitious materials, chemical admixtures and/or fiber reinforcement. The key to achieving a durable, strong concrete is the careful proportioning and mixing of these ingredients. A well graded mix of large, medium and fine aggregates allows the cement to bind the mix more tightly increasing durability and making it more resistant to water, salt and other external forces.
Concrete textures are engineered to stay smooth and quiet throughout a pavement’s life. This enables a better and safer grip and touch point for vehicle tires. With asphalt, aggregates (rocks) dislodge and ravel as it ages. These loose rocks lay on the pavement and reduce your braking ability. Because concrete has a rigid structure, it is safer than other paving systems with shorter braking distances in wet or dry conditions.
Concrete also has a high level of light reflectivity, making it safer to drive at night. In addition, when you have a pavement that lasts 40 years or more, there is less need for repair, particularly for parking lots which can get a lot of heavy use.
And, on a sunny summer day, asphalt, which absorbs heat, can actually burn your (and your pets’) feet! According to the Cleveland Clinic, the ashpalt can get hotter than the surrounding air — and hot enough to cause skin to burn. Concrete, because of its light color, reflects the heat making it much cooler (up to 20 degrees) than an asphalt surface.
Concrete pavement is not only a good pavement choice for environment it is, in fact, the most sustainable solution for many reasons.
- Concrete is 100% recyclable and is often re-used on the same project site. In fact, according to the American Concrete Pavement Association (ACPA), more than 140 million tons of concrete are recycled and reused every year. Concrete can be reused for base material, new concrete, granular fill, and carbon sequestering.
- Components of a fresh concrete surface chemically react with atmospheric carbon dioxide in a process known as carbonation, forming calcium carbonate (limestone). This carbon capture effectively sequesters carbon, removing it from the atmosphere.
- Lighter colored materials have high albedo, which helps them cool the surrounding area. The light color of concrete offers a built-in benefit: it reflects sunlight, reducing the urban heat island effect which has a substantial impact on our health and environment. Asphalt pavement absorbs heat energy and release it back into the environment, raising temperatures and leading to increased air pollution and greenhouse gas emissions.
- Concrete is not petroleum based. There is no odor or stench when concrete pavement is placed or reheated daily by the sun.
- According to ACPA, concrete pavement increases fuel efficiency by three to seven percent for semi-trucks (saving 40 gals/1000 mi. driven) with similar savings in cars and light duty trucks.
- In a study shared by the Coalition for Responsible Roads, researchers from Yale found that under summertime conditions, asphalt may be a greater source of secondary organic aerosols, particulate matter that have been linked to asthma and other insidious public health issues, than gasoline and diesel from motor vehicles combined.
When cost, time, durability, safety and sustainability are factored in, concrete is the clear choice for your pavement needs. If you would like to read more about the benefits of concrete over asphalt, please visit our blog and check out our recent posts on the subject.