Frequently Asked Questions:

1.  What is a asphalt?

Asphalt is a combination of a by-product of crude oil known as binder, dried-crushed rock/gravel and sand, thus giving it a new name of asphalt cement, often referred to as “asphalt”.

2.  How is asphalt made?

Binder, received from the oil refineries, is heated and combined with crushed rock and sand to a temperature of over 300- degrees at an asphalt plant/facility.    

3.  What is Hot Mix Asphalt (HMA)?

Hot Mix Asphalt is the combination heating binder, rock/gravel, and sand together.

4.  What causes asphalt pavement failure?

About 90% of the time when we have pavement failure, it is a problem with the subgrade. Inadequate support in the base and soil directly beneath the pavement can cause alligator cracking and other pavement failures.                                               
 Hot Mix Technology-July/Aug.2006-Pg. 22 Triemstra

5.  Are there special needs to be concerned with when dealing with commercial developers?

Many of the less experienced developers just care about how fast you can do it, and they want it done as cheaply as possible.  Often these lots are under-designed for the loads they will have to carry.  In this situation, the owners are compromising the integrity of the lot because they are so focused on getting the doors open to the shopping center on a certain date.  They aren’t thinking about how a parking lot failure will inconvenience their shoppers later.                                                      
Hot Mix Technology-July/Aug.2006-Pg. 21-White                                         

6.  What is the process for transporting the HMA from a facility to usage at the paving  machine?

The Hot Mix Asphalt is transported via dump trucks to the paving machine on the construction site.  The trucks dump the hot HMA into the hopper on the front of the paving machine.  As the paving machine drops the pavement on the ground, workmen known as “luteman/rakers” spread the HMA  quickly in place so the heavy roller machine can be driven over the fresh pavement before the temperature of the HMA drops below 175-degrees Fahrenheit…the lowest  temperature at which compaction can take place to meet the specified compaction density.  Traffic is generally permitted on the pavement immediately following compaction.  

7.  What happens to the excess HMA mix?

In the event excess mix is produced, the asphalt facility has batch plants which have special heated silos in place to retain extra production for future use. 

8.  What makes asphalt pavement so safe for driving?

Road safety is a major issue for the asphalt contractor; not only when placing the asphalt, but for driving on the surface after placement. Due to the micro-texture of the asphalt, a car tire is able to grip the road more readily and less likely to skid when the brakes are applied.  Asphalt roads, known as “the quiet road”, does not contain expansion joints thereby eliminating road noise that can cause a distraction.  Other features of asphalt are:

• In the year 2000, South Carolina implemented “Open Grade Friction Course” on major roadways to eliminate tire spray during a rain storm and thus giving better traction during wet weather.
• Asphalt is unaffected by winter road safety maintenance because it is impervious to de-icing alts and chemicals
• Asphalt retains heat better than other materials so ice doesn’t form as quickly

9.  Is asphalt environmentally sound?

Yes, absolutely!  Asphalt pavement is 100 percent recyclable and can be made to perform better the second or even third time around. In fact, asphalt is the most recycled product in the United States at 80 percent. That compares to significantly lower percentages for aluminum cans, newsprint, plastic and glass beverage containers, and magazines.

Often when the asphalt contractor removes asphalt from the road, it is re-crushed, mixed  with additional aggregate and binder, and immediately placed back on the road. Should the contractor elect not to follow this method, then the removed asphalt will be taken to a designated area and “stock-piled” for future use.  The hot mix asphalt industry also accepts the following recycled materials: rubber from used tires; slag from the steel-making process; roofing shingles; sand from metal-casting foundries; and recycled cement from buildings.

• In a report to Congress, the Federal Highway Administration estimated that over 70 million tons of asphalt paving material was recycled in 1992.
• Recycling roads not only conserves natural resources and decreases construction time it saves American taxpayers over $300 million each year.
• Asphalt is not soluble or harmful in a water environment.
• Asphalt also prevents pollution from getting into water supplies and protects against disease from waste materials. It can be combined with aggregate to form a voidless and impermeable layer.
• Many states have tested discarded asphalt pavement and determined that it should be categorized as clean fill. Even the Environmental Protection Agency’s Toxicity Characteristics Leach Procedure (TCLP) test, their most extreme and rigorous test for determination of a substance, failed to show any appreciable quantities of toxic materials in pavement materials.

10.  I have seen huge piles of recycled asphalt at various sites, is this safe for the environment?

Most assuredly, yes.

RAP stockpiles help lower fugitive dust emissions.

RAP is often used to suppress dust on unpaved roads

RAP is commonly used as clean fill material in highway construction

RAP is an important tool for environmental stewardship                                                                                                                        NAPA-SR-190-3.23.06

12.  Why are so many asphalt plants necessary?

When a road in South Carolina needs resurfacing, SCAPA contractor members want to give you the best and safest road money can buy.  To be able to meet that obligation, asphalt plants are located throughout the state, near road construction sites to ensure the mixture maintains the required temperature of at least 300 degrees when leaving the facility.  Remember, the higher the heat, the better the compaction; the better compaction, the better the quality of the pavement .

13.  I’ve seen asphalt used for golf cart paths and parking lots, at track meets, etc.  Can you   name some other placed it might be used that one would not readily think of?

Yes. Asphalt has a variety of uses, including:

Airport runways, greenway trails, bicycle paths, basketball and tennis   courts.

In addition to the agricultural area for paving cattle feed lots, poultry house floors, barn floors, and green house floors, it is also used 

In lining surfaces from fish hatcheries to industrial retention ponds.

In rail-road-beds for transit systems.

In sea walls, dikes and groins to control beach erosion. Its strength, waterproofing capability and inertness to seawater helps prevent the eroding action of tides and waves.

Sources: National Asphalt Pavement Association, N.C. Department of Environment and Natural Resources, North Carolina State University, S. C. Department of Health and Environmental Control.

14.  I know you have to be concerned with utilities when paving streets, but what about driveways, greenway trails, bicycle paths, tennis courts, etc.  Do I really need to call the digger’s hotline or notify the utility people? 

We would recommend contacting them.  Simply because, “an ounce of prevention is worth a pound of cure”. If you hit a utility line, you can be in big trouble.  When you are doing excavation, you need to be very careful.  A utility fine can be very costly.

15.  How does the asphalt compare with concrete as far as dollar volume?

It does save taxpayers dollars. In a 3-year analysis conducted by the Florida Department of Transportation, initial construction of an asphalt pavement cost $544,981 to concretes $766,729.  After wear and tear and maintenance, the residual value of the asphalt pavement was 203% more than the concrete road.

While each road needs to be analyzed based on its own merits, for maintaining roads, the Florida Department of Transportation calculated their routine annual maintenance costs as $132 per lane mile for asphalt pavement and $261 per lane mile for concrete pavement.

HMA gives the best return on investment of any paving material.  HMA pavements can be cold milled and recycled which saves costly readjustment of manholes, curbs and sewer drains when rehabilitating urban streets.