What is asphalt?
Asphalt, also known as hot mix asphalt (HMA), is made from dried crushed rock and asphalt cement, which is a mixture of petroleum compounds produced by oil refineries. Known uses for asphalt go as far back as six thousand years. Archaeologists have established that asphalt is one of the oldest adhesives known to man. It was used to make bathing pools, reservoirs, and canals watertight. Asphalt was used in Mesopotamia. Bricks for the great wall of Babylon were joined with asphalt. Joints of ships were sealed with asphalt. The Bible story of Noah’s ark claims that Noah used pitch, another name for asphalt, to waterproof the joints in the ark. Asphalt was even used in Egypt to embalm mummies. The advent of the automobile required hard road surfaces. After 1918, when the number of cars and trucks began to increase rapidly, asphalt was taken from asphalt pits and used for road surfaces. However, most of the asphalt used today is made from crude oil. Surfaces of 90% of all paved roads in the
Asphalt is a thick brownish or black substance derived from the same crude oil which produces kerosene, gasoline and vinyl. It is literally scraped from the bottom of the barrel after all other petroleum-based products have been refined or processed. Asphalt is at least 80% carbon, which explains its deep black color. Sulphur is another ingredient found in the tar-like asphalt, as well as some trace minerals. Asphalt is primarily used as a sealant for rooftops and a durable surface for roads, airport runways, playgrounds and parking lots. The tar from the crude oil is usually mixed with sand or gravel (often called aggregate) to form the finished product we call asphalt. The black tar forms a strong adhesive bond with the aggregate, which makes it durable. When used in road construction, asphalt is usually poured over a bed of heavier aggregate in a heated state, then pressed into place by an extremely heavy steam roller. Once the fresh asphalt cools to ambient temperature, it becomes
