What is Asphalt?
Asphalt is a dark brown or black cementitious material which is a natural constituent of most crude oils found throughout the world.
What is Tar or Coal Tar?
A dark brown to black cementitious material produced by the destructive distillation of Bituminous coal. This product is not used in the Industry.
What is Aggregate?
A hard granular material of mineral composition such as sand, gravel, or crushed stone used in prescribed graduated fractions.
What is Asphalt Pavement?
Specification grade asphalt (binder) is heated and combined with specification crushed dried sand-gravel in a quality controlled mixing plant. The asphalt pavement mixture is then loaded onto trucks for delivery to construction sites or kept in storage silos.
What is an Asphalt Plant?
A manufacturing facility that produces asphalt paving
What is Reclaimed Asphalt Pavement (RAP) Mix?
Removed asphalt (commonly called old Blacktop) that is used in the recycling of asphalt pavements along with new aggregate and new asphalt (binder) being added. According to a study published by the Federal Highway Administration and the Environmental Protection Agency, asphalt pavement is America’s most recycled product. The asphalt industry recycles 80.3 million tons of its own product every year, the largest tonnage of any industry. And, asphalt’s 80% recycling rate is higher than any other material’s.
Is Asphalt and Hot Mix Environmentally Sound?
Yes, in fact it is the most recycled product in the USA at 80 percent. That compares to significantly lower percentages for aluminum cans, newsprint, plastic and glass beverage containers, and magazines. Asphalt roads are removed, recrushed, mixed with additional aggregate and asphalt cement (binder), remixed, and placed back on the road. In fact, in 2002, the EPA de-listed asphalt plants as a major source of emissions based on data leading them to conclude that no asphalt concrete manufacturing facility has the potential to emit hazardous air pollutants (HAP) approaching major source levels. See the EPA Delisting Report PDF
for more information.
How Can Asphalt Reduce Noise Pollution?
Many studies over the years have shown that asphalt pavements reduce the sound produced at the tire-pavement interface. Special surfacings such as open-graded friction course (OGFC), stone matrix asphalt (SMA), and gap graded blends provide excellent skid resistance while reducing highway noise. When the concrete Superstition Freeway in the Phoenix area was overlaid with open-graded mixture, the reduction in noise was so dramatic that residents of other areas began demanding to have the concrete freeways through their neighborhoods get the same treatment. Arizona’s state and local governments soon responded with a $34 million resurfacing plan that will encompass 115 miles of existing concrete freeways in Maricopa County, which surrounds Phoenix, the state capital. Several European countries are using asphalt pavement as a means to mitigate noise issues on their roadways at the source.
What is Flexible Pavement?
The ability of an asphalt pavement structure to conform with loads and withstand temperature changes. Generally, flexibility of the asphalt paving mixture is enhanced by a slightly higher asphalt content.
What is a Pavement Structure?
A pavement structure with all its’ courses of asphalt-aggregate mixtures, or a combination of asphalt courses and untreated aggregate courses placed above the subgrade.
How Can Asphalt Pavements Reduce Delays for Road Users?
Paving with asphalt cuts construction project time significantly and eliminates long curing times. As a result, traffic flows more smoothly, impact on commerce is minimized and safety hazards are reduced. Asphalt paving projects can be planned and carried out to take advantage of low-traffic periods, like nights and weekends, minimizing the project’s impact on motorists, residences and businesses.
What Pavement Type Costs the Taxpayers Less?
For both the short term and the long haul, asphalt pavement saves money on construction and maintenance. Research shows that selecting the right paving material, like asphalt, will result in lower initial costs and long term costs to the motoring public compared to competing paving media. A comparison by the Florida Department of Transportation calculated initial construction costs to be nearly 30% less for asphalt than concrete. The department’s figures on long-term residual value of the asphalt pavement, meanwhile, were even more impressive: With proper maintenance, the department concluded that asphalt pavement’s maintenance requirements, at about half those of concrete, gave asphalt an advantage, the Florida highway officials concluded. Similar savings have been documented in other states including Kansas and North Dakota.
What is Full-Depth Asphalt Pavement?
The term FULL-DEPTH (registered by the Asphalt Institute with the U.S. Patent Office) certifies that the pavement is one in which asphalt mixtures are employed for all courses above the subgrade or improved subgrade.
Can Asphalt Pavement Be Used For Heavy Loads?
Asphalt pavement is the pavement of choice for big or small parking lots, expansive shipping yards, areas for material handling, railroad facilities, airports, etc., because it can take the weight and the punishment.
Is Asphalt Tough Enough To Take The Punishment of Heavy Planes?
Yes. Just ask the people who operate some of the busiest airports in the country. Some of the commercial airports with asphalt runways include Baltimore-Washington International, Lindbergh Field in San Diego, McCarren International (Las Vegas), Memphis International, Newark International, Oakland International, O’Hare International (Chicago) and San Francisco International.
How Has Asphalt Pavement Been Used For Airport Runway Reconstruction?
In many ways! Here are a few:
- Between 85-90% of all runways at the nation’s 3,364 commercial airports are surfaced with asphalt, according to the Federal Aviation Administration. Busy commercial airports such as those in Boston, Las Vegas, Newark, Oakland, San Francisco, and Toronto have main runways surfaced with asphalt.
- Runway 4R-22L at Newark International Airport was completely reconstructed in just 10 days. The contractor placed 105,000 tons of asphalt pavement, meeting extremely aggressive paving specifications. In addition to paving, the contractor removed and replaced all runway lights and saw-cut and sealed all joints on the 9,300-foot-long, 150-foot wide runway.
- In rebuilding the main runway at Eglin Air Force Base in Florida, the contractor met 100 percent of the smoothness specs.
- At the Front Range Airport in Colorado, the contractor used a paver with a computerized grade control to place a 4-inch overlay, and corrected an average of 25 inches per mile of deviation to 2 inches per mile.
- Two 7,500-foot-long runways at the Marine Air Corps Station, Cherry Point, North Carolina needed paving. The Marine Air Corps asked the contractor to minimize transverse joints on the surface, so the contractor built the runways with no joints whatsoever.
Where Else Can Asphalt Pavements Be Used?
Streets and Highways:
According to the Bureau of Transportation Statistics, 94% of the 2.27 million miles of paved roads and highways in the U.S. are surfaced with asphalt.
Race Tracks: Of the 35 NASCAR race tracks across the country, 31 are paved with asphalt surfaces.
Industrial Applications: Even where the traffic is heaviest, such as at port container yards, timber yards, and rail transfer yards, asphalt paves the way.
Bike Paths, Sidewalks, and Recreational Facilities: Asphalt pavement is ideally suited for providing paths that are aesthetically pleasing and blend well with natural settings.
Hydraulic Structures: Fish hatcheries, drinking water reservoirs, pond linings, and canal linings count on asphalt for a long-lasting, contamination-free surface.
What is Deep Strength Asphalt Pavement?
A flexible asphalt pavement in which the asphalt base course is placed in one or more lifts of 4 or more inches compacted thickness.
What is Design Thickness?
The total pavement structure thickness above the subgrade.
What is Capillary Action?
The rise or movement of water in the voids of a soil or granular material caused by capillary forces.
What is Hydrostatic Pressure?
The pressure in a liquid under static conditions; the product of the unit weight of the liquid and the difference in elevation between the given points and the free water elevation.
What is Stone Matrix Asphalt (SMA)?
A tough, stable, rut-resistant, gap-graded European technology mixture, originally known as Split Mastix Asphalt.
What is Long Lasting or Perpetual Asphalt Pavement?
Perpetual Pavements use multiple layers of highly engineered asphalt pavement to produce a safe, smooth, long-lasting road. The asphalt pavement design begins with a strong yet flexible bottom layer constructed on a good foundation. The bottom layer resists tensile strain caused by traffic, and thus stops cracks from forming in the bottom of the pavement. A strong intermediate layer completes the permanent structural portion, and a final layer of rut-resistant asphalt pavement yields a surface that lasts many years before scheduled restoration. A Perpetual Pavement provides a durable, safe, smooth, long-lasting roadway without expensive, time-consuming and traffic-disrupting reconstruction or major repair. The concept is similar to that of a house that periodically may need to be painted or re-roofed, but that still stands the test of time.
What is Rubblization?
Rubblization is a cost-effective means of rehabilitating deteriorated portland cement concrete (PCC) pavements. The concrete is broken into pieces, and then it is overlaid with asphalt pavement. It minimizes delays and allows for construction during off-peak hours. The rubblized roadbed is left in place, so that it does not have to be trucked off to a landfill. This not only saves landfill space, it eliminates many trips by trucks, saving diesel fuel and reducing traffic congestion. The new asphalt pavement will remain smooth, safe, and quiet for years.
SUMMARY OF MINNESOTA RESEARCH FINDINGS
MAPA commissioned Erland Lukanen of ERES Consultants to evaluate the performance history of Asphalt Pavements with Aggregate Base and of Portland Cement Concrete Pavements on the Mn/DOT Highway system. The reports on both of these projects are now complete and the results are interesting indeed.