Question 1

Are concrete pavements durable?

Accepted Answer

Properly designed concrete pavements can last more than 40 years.

In general, asphalt pavements deteriorate at a rate of 1.5 to 2.5 pavement condition index (PCI) points per year—an average of 2 points—whereas concrete pavements only deteriorate at a rate of 0.5 to 1.2 PCI points per year.

Question 2

How does asphalt maintenance compare to concrete pavement maintenance?

Accepted Answer

Asphalt pavement requires mill and fill about every 10 years to keep roughness under control; even then, it experiences periods of poor condition compared to concrete, which can be diamond ground every 25 years and remain fairly smooth.

Question 3

How does the cost of concrete pavement compare to the cost of asphalt?

Accepted Answer

Because pavements treated with concrete pavement preservation techniques stay smoother longer, they mitigate maintenance costs to highway users as well as provide a quieter, better ride for motorists.

Independent studies show concrete pavements cost 50% less in ongoing maintenance than asphalt.

Question 4

Is concrete a safe driving surface?

Accepted Answer

Safe and sure driving depends on how well tires grip the road. Grooving a pavement’s surface through diamond grinding increases traction, reduces hydroplaning, minimizes splash and spray, and provides a more effective braking surface.

Concrete also has superior light reflectance which makes it safer to drive on at night. This has energy-saving benefits, as well: according to a Minnesota research study, roadway illumination demands are 40% to 50% lower for concrete pavements than for asphalt pavements.

Question 5

What are the sustainability benefits of concrete pavement?

Accepted Answer

With its lifespan of 40+ years, concrete pavement is long-lived and durable, making it inherently sustainable. It is also resilient, making it a good choice in terms of disaster recovery and exposure to extreme weather.

Concrete even offers sustainability benefits during materials sourcing and construction. It uses locally sourced raw materials and is not dependent on foreign, petroleum based products such as oil derivatives. Concrete production supports the local economy. Concrete is 100% recyclable and is often re-used on the same project site. Concrete can be reused for base material, new concrete, or granular fill.

Furthermore, concrete sequesters carbon. As concrete paving ages, it absorbs carbon dioxide, helping reduce the amount of CO2 in the atmosphere. This process is called carbonation. The amount of CO2 sequestered through concrete carbonation is calculated to be between 0.2-0.3 lbs/ft2 of surface area in 50 years – roughly 14,000-20,000 lbs. per lane-mile.

Concrete pavement preservation with diamond grinding reduces green-house gas emissions even further. It minimizes overall construction activity, promotes vehicle fuel efficiency by providing smooth surfaces and, with timely treatment, can more than double the amount of CO2 sequestered.

Paving with concrete can also reduce environmental impact by reducing waste. In addition to the recyclability of rubble, when a concrete pavement is diamond ground, no debris is left behind.

Question 6

Are fuel savings associated with concrete pavements?

Accepted Answer

The CSHub has identified two key factors that influence how pavements affect fuel consumption: deflection and roughness. Deflection of a road surface creates slight depressions that vehicles have to use additional force to roll out of. Extra fuel is required to exert that force and, over many miles, this adds up. Pavement roughness causes a similar situation, in which too many points of contact between the tire and the pavement are eliminated. This means that vehicles traverse smooth and rigid surfaces more efficiently than flexible or rough surfaces. In addition to negatively impacting vehicle control and safety, the uneven contact increases the rolling resistance, and thus the amount of fuel required to overcome the resistance. Deflection has the most impact on trucks and heavy vehicles, while roughness has the greatest effect on fuel consumption for cars.

According to CSHub, these inefficiencies are causing an estimated 700 million gallons per year of excess fuel consumption on the U.S. road network. Most of that excess is caused by pavement roughness.

Question 7

Is tining the same thing as diamond grinding?

Accepted Answer

No; transverse tining was an early solution for providing traction on concrete pavements. The interaction between transverse grooves and tires created noise, however. The longitudinal texture produced by diamond grinding, on the other hand, reduces noise because it is oriented in the direction of driving. Diamond grinding used as a concrete pavement preservation technique removes noisy transverse grooves and makes pavements quieter.

Question 8

Is milling the same thing as diamond grinding?

Accepted Answer

No; milling is a demolition and removal technique, not a restoration technique. Milling is an impact process that chips small pieces from the pavement surface, whereas diamond grinding does not fracture aggregates or otherwise harm the pavement structure. Diamond grinding contacts a pavement surface nearly 27,000,000 times per square yard, on average. This results in gentle abrasion of the concrete surface and avoids the risk of introducing microcracking of the aggregates.

Question 9

Is concrete a quiet pavement?

Accepted Answer

Typical building codes for noise in the United States require 45 to 55 dB(A) in living spaces during the day. When using concrete pavement, engineers can achieve this goal through diamond grinding, particularly the Next Generation Concrete Surface (NGCS) method of grinding. (NGCS is a hybrid texture that resembles a combination of diamond grinding and longitudinal grooving. It was developed by Purdue University between 2006 and 2008 and funded by the concrete industry.)

Asphalt rubber, which has a reputation as a very quiet road surface, is slightly quieter than diamond ground pavement early in its life, but in time becomes louder than diamond-ground pavement, which retains its quiet characteristics for all its life. Since a three-dBA difference or greater is needed to demonstrate a perceived difference in noise, this slight early-on advantage is insignificant after only a few years.

In 2003, ADOT created the largest quiet pavement research program in the U.S. After 15 years, this research demonstrated that asphalt rubber increased approximately ½ dBA per year in noise level. This means that in ten years it will be 1.5 times louder than when constructed.

Question 10

Is concrete cooler than asphalt?

Accepted Answer

Lighter colored materials like concrete have high albedo, which causes them to reflect heat instead of absorbing it. Therefore, concrete can help reduce urban heat island effect. Check out this video. (https://youtu.be/nc9ywdt-u_k)

Results of a Maricopa County medical study reporting on pavement burns incurred during the EMT process indicated that human skin can burn within one second when exposed to pavement temperatures of 158 degrees Fahrenheit. During the summer, asphalt pavement temperatures were noted in the study as getting very close to this threshold. The study also reported that asphalt pavements were hotter than concrete during a 24-hour period.

Question 11

Does diamond-ground concrete cause tire wear?

Accepted Answer

Diamond grinding is utilized in all 50 states with over 20 million square yards ground annually and no reports of excessive tire wear attributed to the use of this surface.

Additionally, vehicle maintenance costs include more than just tire wear. Driving on rough roads due to asphalt rubber delamination and potholes damages tires and vehicle suspension components, wrecks alignment, chips paint and breaks windshields.

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