Warm mix is a relatively new technology that enables plants to produce asphalt at 50-100 degree lower temperatures than conventional asphalt. As a result, less energy (fuel) is needed to produce it which results in fewer emissions. In addition to it's environmental benefits, warm-mix asphalt provides many paving benefits such as the ability to: get better compaction, pave roads in lower temperatures, haul asphalt for longer distances, and use more recycled content in the mix. All of Virginia Paving plants are outfitted with this technology and 2011 marked the highest producing warm-mix year for Virginia Paving yet.
Hot mix asphalt is the paving material of choice for numerous applications—it provides a very smooth, quiet ride. It’s used to construct heavy duty pavements on interstate highways (I-495 and I-95), on runways at airports (Washington Dulles International Airport and Ronald Reagan Washington National Airport), and on bridges and interchangers (Woodrow Wilson Bridge and Springfield Interchange). It also serves other purposes such as liners for drinking water reservoirs and fish hatcheries. Hot mix asphalt is also used as the paving material for parking lots and driveways and it is used on playgrounds, tennis courts, hiking/bike trails, and golf course paths.
First, it’s very easy to make, transport and apply. Secondly, hot mix asphalt can be driven over almost immediately after being applied to a surface. (See FAQ below: Please describe a typical repaving project) Concrete, on the other hand, can take several days to cure. In the Washington Metropolitan Area, quick turnaround on road construction and repair is paramount for commerce and commuter purposes.
Hot mix asphalt consists of a mixture of stone and recycled asphalt pavement (about 95 percent) and a glue-like liquid asphalt (about 5 percent) which holds the stones together in a tough matrix that resists the stresses induced by traffic and other loadings. By varying the size and shape of the stones and the type and liquid amounts, hot mix asphalt is a unique product that is safe and cost-effective manner.
The process is quite simple. Stone, a.k.a. aggregate, recycled asphalt pavement, and liquid asphalt is mixed in a 400+ degree cylinder drum. The end product is hot mix asphalt. Click here to see a plant diagram.
Yes. Hot mix asphalt is not considered a major source of pollution by the Environmental Protection Agency (EPA). This designation means that, in the opinion of certified and accredited professional toxicologists at the EPA, even the largest hot mix asphalt plants do not emit significant quantities of air pollutants.
97 percent of Virginia’s paved roads are surfaced with asphalt. Nationwide, 94 percent of the 2.3 million miles of paved roads are surfaced with asphalt.
One of the important facts about hot mix asphalt is that it is 100 percent recyclable. In Virginia, most asphalt mixes specified for use on roadways allow for over 20 percent of the material to be recycled asphalt.
Hot mix asphalt used as a base material can have over 25 percent recycled asphalt pavement (RAP). The use of RAP in hot mix asphalt provides a number of benefits: 1) it reduces the amount of virgin material used in the mix, thereby preserving natural resources (stone and liquid asphalt); 2) since it is 100 percent recyclable it does not need landfill space for disposal; and 3) recycling hot mix asphalt results in substantial savings to taxpayers (for road work) and other users.
Another benefit of hot mix asphalt is that it can provide the lowest levels of traffic and tire noise. This can be extremely cost effective in urban areas where the use of sound walls may otherwise be necessary.
The quickest way to repave a roadway is through the mill-and-fill approach. This approach dramatically reduces the amount of time a roadway needs to be tied up as a work zone with all of the related traffic delays and safety concerns.
Milling machines (the very tall, Star Wars-looking machines with tracks on the bottom) grind out the worn out asphalt then transfer the material to a haul truck for delivery back to the asphalt plant for recycling into new mixes. Much of the grade and slope is restored as part of this process.
Meanwhile, immediately behind the milling machine, pavers (the very slender and wide machines that the dump trucks back into) can replace the removed material with fresh mix and have it compacted (by the heavy two-wheeler rollers) and turned back over to traffic in a very short period of time.
Another advantage in addition to the short construction time, restoration of grade and slope and ability to reuse the milled up asphalt is the ability to maintain a constant pavement elevation to keep bridge clearances and guardrail tolerances in check.
Without question, the mill-and-fill technique for asphalt pavement restoration is one of the great advantages of paving with hot mix asphalt.
In the Northern Virginia region, a newly constructed asphalt road can last for decades with only the top surface course being removed (milled) and replaced every 10 to 20 years depending on traffic volumes.
Due to the high daytime traffic volumes in the Washington Metropolitan Area, the majority road work takes place at nighttime between April and October to avoid shutting down important commuter routes. The Washington D.C. Metropolitan Area has become the #1 worst traffic in the U.S., tied with Chicago.
Today, most transportation contracts require nighttime paving to ease daytime traffic congestion. Paving at nighttime is also much safer for the men and women working on the road. Fewer cars and trucks significantly decreases the probability of an accident. Safety is priority one at Virginia Paving.
A pothole forms when a simple hole or crack in the road surface or base begins to expand due to water penetration (usually due to water turning to ice and expanding during cold weather). Coupled with the constant pounding from auto and truck traffic, potholes form very quickly. If unattended, they can damage vehicles very easily.
Asphalt is the most recycled product in the U.S.—more than aluminum cans, bottles and newspapers.
How many airport runways are paved with asphalt?
90 percent of all runways at the nation’s 3,364 commercial airports are surfaced with asphalt.