Environmental Benefits of Paving with Asphalt
Posted by Jesse Willoughby on Thu, Jun 04, 2009 @ 04:50 AM
Recycling
Hot Mix Asphalt gives the best return on investment of any paving material. But beyond just having that fact that it saves money, it also has environmental benefits.
Because the main ingredient in asphalt is oil, its price has increased dramatically in the last several years. Five years ago, government agencies paid $35 to $40 a ton for asphalt. However, now the price has escalated to over $90 a ton, and it is predicted that the price of asphalt will continue to climb. This has led to an increased demand for recycled asphalt which is lower in price and widely available. Asphalt and tar recycling has also become more popular because of environmental concerns. Recycled asphalt simply produces a less negative environmental impact because it is not being placed in landfills.
Hot Mix Asphalt(HMA) pavements are 100 percent recyclable and are America's most recycled product. Approximately 80 million tons of Hot Mix Asphalt are recycled each year. Compare this to any other recycled products. Hot Mix Asphalt pavements are truly environmentally friendly.
HMA pavement recycling is more cost effective than using only virgin or new materials. The quality of a recycled asphalt pavement is as good, or even better, than brand new pavement.
Hot Mix Asphalt pavement recycling not only conserves our precious natural resources and speeds construction, it also saves American taxpayers over $300 million a year.
HMA pavements which are not recycled must be disposed of, usually in a landfill. Transporting old asphalt pavements to landfills does not make best use of a product that can be recycled. HMA pavements can be recycled numerous times.
Currently, even most new asphalt has between 15 and 20 percent of crushed, recycled asphalt mixed into it. Because of this, asphalt has now surpassed aluminum as the most widely recycled material in the world.
ASPHALT IS AN ENVIRONMENTALLY SOUND PRODUCT
Environmental Liners
Asphalt paving materials have been used to line the surfaces of everything from fish hatcheries to industrial retention ponds. In the case of fish hatcheries, an inert material was needed that would not chemically react with the water. This allows fish and game experts to precisely monitor and control the environment during the delicate stages of incubation and early growth for various fish species.
- For example, Oregon and Washington state fish and wildlife agencies began using HMA to line their fish rearing ponds in 1987. Typically 1/2-acre in area, the ponds are home to chinook salmon and other fry for about 18 months before the fish are released into rivers and streams. Both the Washington and Oregon state agencies are pleased with the effectiveness of the HMA liners and plan to use them for additional fish hatcheries in the future.
For decades asphalt paving materials have been used as liners for water reservoirs.
- For example, The Metropolitan Water District of Southern California (MWDSC) has been using HMA-lined water reservoirs for more than four decades. Currently, the California Water Resources Board is completing construction on the Devil's Canyon Reservoir to store MWDSC drinking water. The 1 9-inch thick asphalt liner for the huge facility will hold 800-acre-feet of water. The East Bay Municipal Utility District (EBMUD) in Oakland, California, has also been using HMA to line domestic water supply reservoirs since the 1 950s. A total of ten reservoirs store water in the EBMUD system.
Asphalt binders have also been used to line water pipes that supply potable water to humans.
When used for industrial retention ponds, the inertness of asphalt paving materials keeps liquid industrial waste material from percolating into the soil. This gives industry time to treat the liquid waste, and if needed, provides a platform with which to bring in mobile equipment to move the material to a processing location.
The ability of asphalt paving materials to be both chemically inert and strong enough to provide a structure for heavy equipment accounts for its use as both a landfill liner and cap. In landfills lined with asphalt paving materials modified earthmoving equipment can be employed to organize and compact landfill waste without fear of breaking the impermeable shell between the solid waste material and the soil.
Clean fill
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 Leaching Procedure (TCLP) test, their most extreme and rigorous test for determining the toxicity of a substance, failed to show any appreciable quantities of toxic materials from asphalt pavement material.
Recreational Uses
HMA pavements are a perfect fit for the recreational industry. For years HMA has been used to pave running tracks, bicycle and golf cart paths, in addition to its traditional use for basketball and tennis courts.
Recently, there has been a move in the recreation marketplace to combine exercise with nature. Throughout the country old nature paths and abandoned rail lines are being converted into thoroughfares for bicyclists, roller skaters and roller bladers, besides the occasional pedestrian who wants to view nature while they exercise.
Asphalt pavements provide a safe and durable surface with which to accommodate both wheeled and foot traffic.
Other Uses
HMA is also used to pave cattle feed lots, poultry house floors, barn floors, and greenhouse floors. Asphalt not only provides an all-weather platform, it also provides protection against disease from waste materials. Asphalt is easy to clean and prevents pollution from getting into water supplies.
Asphalt mixtures are also used in sea walls, dikes and groins to control beach erosion. Its strength, waterproofing capability and inertness to sea water helps prevent the eroding action of tides and waves.