A Brief Look At The History of Asphalt
Today, this dark, resilient material covers more than 94 percent of the paved roads in the United States; it’s the popular choice for driveways, parking lots, airport runways, racetracks, tennis courts, and other applications where a smooth, durable driving surface is required.
Called at various times asphalt pavement, blacktop, tarmac, macadam, plant mix, asphalt concrete, or bituminous concrete, asphalt pavements have played an important role in changing the landscape and the history of the U.S. since the late 19th century.
But the story of asphalt begins thousands of years before the founding of the United States. Asphalt occurs naturally in both asphalt lakes and in rock asphalt (a mixture of sand, limestone, and asphalt).
The first recorded use of asphalt as a road building material was in Babylon around 615 BCE,
in the reign of King Nabopolassar. In A Century of Progress: The History of Hot Mix Asphalt, published by National Asphalt Pavement Association in 1992, author Hugh Gillespie notes that “an inscription on a brick records the paving of the Procession Street of Babylon, which led from his palace to the north wall of the city, ‘with asphalt and burned brick.’”
Many centuries later, Europeans exploring the New World discovered natural deposits of asphalt. Writing in 1595, Sir Walter Raleigh described a “plain” (or lake) of asphalt on the Island of Trinidad, off the coast of Venezuela. He used this asphalt for re-caulking his ships.
Laying the Foundation for Asphalt Roads
Despite these early uses of asphalt, several hundred years passed before European or American builders tried it as a paving material. What they needed first was a good method of road building.
Englishman John Metcalf, born in 1717, built 180 miles of Yorkshire roads. He insisted on
good drainage, requiring a foundation of large stones covered with excavated road material to raise the roadbed, followed by a layer of gravel. Thomas Telford built more than 900 miles of roads in Scotland during the years 1803–1821. “He perfected the method of building roads with broken stones, laid to a depth according to the weight and volume of traffic it would have to carry,” Gillespie writes.
Asphalt Roads Come to America
The first bituminous mixtures produced in the United States were used for sidewalks, crosswalks, and even roads starting in the late 1860s. In 1870, a Belgian chemist named Edmund J. DeSmedt laid the first true asphalt pavement in this country, a sand mix in front of the City Hall in Newark, New Jersey. DeSmedt’s design was patterned after a natural asphalt pavement placed on a French highway in 1852.
DeSmedt went on to pave Pennsylvania Avenue in Washington, DC, a project that included 54,000 sq. yds. paved with sheet asphalt from Trinidad Lake Asphalt. The durability of this pavement proved that the quality of the asphalt found in the Americas was as good as that imported from Europe.
Changing Techniques in Production and Construction
Until about 1900, almost all asphalt used in the U.S came from the natural sources of Lake Trinidad and Bermudez Lake in Venezuela. Refined petroleum asphalts, used initially as an additive to soften the natural asphalt for handling and placing, made an appearance in the mid-1870s and slowly gained acceptance. By 1907, production of refined asphalt had outstripped the use of natural asphalt.
Meanwhile, as the automobile grew in popularity, local and state governments were besieged by requests for more and better roads. This demand led to innovations in both the production and laying of asphalt. Roadway testing gradually became an accepted practice thanks to the efforts of Logan Waller Page, who had studied the procedures in France.
The first asphalt facility to contain virtually all the basic components of those of today was built
in 1901 by Warren Brothers in East Cambridge, Mass. (It lacked only a cold feed and pollution control equipment.) The first drum mixers and drum dryer-mixers, which came into use around 1910, were Portland cement concrete mixers that were adapted for use with HMA. Mechanization took another step forward in the 1920s with the improvement of cold feed systems for portable and semi-portable systems. Vibrating screens and pressure injection systems were added in the 1930s.
During World War II, asphalt technology improved at a great pace, spurred in part by the need of military aircraft for surfaces that could stand up to heavier loads. After the war ended, and families moved to the suburbs, road building became a huge industry. In 1956, Congress passed the State Highway Act, allotting $51 billion to the states for road construction.
Contractors needed bigger and better equipment. Pavers added electronic leveling controls in the 1950s, and automated screed controls in the early 1960s. Extra-wide finishers, capable of paving two lanes at once, made their debut in 1968.
Over the last 30 years, the versatility of asphalt has led to its increased use in other applications. HMA airport runways are finding increased acceptance in the United States, since they provide passengers more comfortable takeoffs and landings, dramatically cut back on runway maintenance, and allow for much faster construction time. Pavements constructed of high-durability HMA mixes are used increasingly for freight yards, where they stand up to heavy static loads.
HMA is also used worldwide as a practical solution to water storage, flood control, erosion, and conservation problems. Asphalt has been approved by the Environmental Protection Agency and used successfully as a primary liner for both sanitary and hazardous-waste landfills. It is also used to line drinking water reservoirs and fish hatcheries in California and Washington.
Meanwhile, the industry continues to benefit from improvements in design and production. Since the mid-1980s, the industry has developed advanced pavement materials including Open Graded Friction Course (OGFC), Superpave, and Stone Matrix Asphalt (SMA), also called gap-graded Superpave. Engineering control systems placed on asphalt pavers beginning in 1997 have improved conditions for workers at the paving site.
Pavements being built today can be engineered to meet a variety of needs — for less noise, greater durability, enhanced skid resistance, reduced splash and spray in rainy weather, and a smoother ride than ever before.
"History of Asphalt"
National Asphalt Pavement Association
Date of Access, 5/30/2017
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