The history of road starts with the history of humanity. Advancements in road technique were seen after the invention of the wheel in 5000 B.C. The first significant roads of the history were encountered in Mesopotamia in 3500 B.C. The roads that were found to have been built in Crete in 1500 B.C. and between Babel and Egypt in 359 B.C.

The efforts of the Rome Empire to expand its territory gave rise to advancements in the road construction technique. The roads constructed back in those years were 4.50 meter wide with sidewalks on both sides.

In the second half of the 18th century, a rapid progress was made in the road construction practices and the roads similar to the ancient Roman roads started to be built. However, due to lack of the materials used in the era of Rome and hardships in workmanship, the roads constructed using large block stones gradually diminished and new methods and studies for the use of stone in road construction were initiated.

As a different method for use of the stone in the road construction, J.L. Mc Adam (1756-1836) of Scotland used crushed stone as road construction material, and, thus, the Mc Adam type of road came into being which is also used in our country. In these types of roads, the upper layer is built by squeezing the crushed stone using a roller and filling the gaps using the paste composed of stone dust and water.

In the same years, new methods were developed by Pierre Tresaguet (1716-1796) in France and the roads with a cross-section similar to Mc Adam type were built. Also, in the same era, a school giving lectures about the roads construction was opened in France during those years.

19. After the invention of the locomotive at the start of the century, the progress in road construction slowed down, yet roads were built between the railroad stations and the neighboring settlements in the second half of the century. In the roads built in these years, no important change in terms of coating took place, Mc Adam type coatings that were further advanced in terms of granulometry and squeezing were used.

The invention of the automobile in the 20th century and extended use of it in the transportation services after the 1st World War revived the land road construction and the construction technique developed faster that it was in the past in line with the vehicle technology.

The Mc Adam type of coatings that were able to resist the tires of the vehicles without motor were inadequate for the motor vehicles, particularly the bandage effect, and a need for new layers and a binder particularly in the coating layer arose in the road construction techniques. As a result, coatings composed of bitumen and concrete roads with cement binder that offer a better rolling surface and have a longer useful life.

Throughout the history, the asphalt was used as the cement of the coating materials and water-resistant objects. The asphalt is one of the products of the nature with the highest number of usage fields. Te asphalt is one of the oldest engineering materials of the humanity. Although its use in road construction does not date back to ancient times, in 6000 B.C., Sumerians produced asphalt nearby the cities called Sodom and Gomore and used the asphalt produced as mortar material. In 2600 B.C., the asphalt was used as the water-resistant material by the Egyptians. In the ancient times, asphalt was widely used as mortar and coating material, for tar coating in the ships and as waster insulation material in several applications.

As a result of the invention of the automobile 1900s and perception of the asphalt as a cheap and infinite material, it started to be widely used in the construction of the modern roads and in many other applications.

The asphalt used today is a natural component of the oil. The crude oil extracted form the wells is divided into its components in the refineries. After this basic procedure, the components are refined again and converted into several different products. These products include, namely, gasoline, lubricant, paraffin and asphalt. The asphalt is composed of the wastes that came into being after dilution of the crude oil. The finished product, asphalt, used in modern road construction, is produced as a result of processing this waste material together with the crushed stone (aggregate), water and bitumen (asphalt cement).

The asphalt cement, or in its technical name, bitumen, used for binding the crushed stones in the urban and rural roads needs to be treated for easy processing since it may not be used under normal temperature and is not fluid enough. The bitumen to be used in the surface coating is general thinned in two different ways.

One of these methods is adding gasoline, diesel or paraffin to the bitumen within the refineries and thinning the material, thus, rendering it fluid. The bitumen that is generated in this way is named "liquid oil asphalt". The second method is the method of thinning the bitumen with water in a special mill, which is widely used in the developed countries. The bitumen that is generated in this way is named "asphalt emulsion".

The gasoline, diesel or paraffin contained in the liquid oil asphalt is emitted to the atmosphere during the application, thus causing air pollution. These types of binders (bitumen) which are forbidden in the developed countries are, unfortunately, widely used in Turkey. Also, liquid oil asphalt is more expensive than the emulsions due to the oil products they contain. Since the asphalt emulsions are composed of the combination of the water and bitumen, they are environment friendly materials.

Being one of the oldest road construction materials, the asphalt enables high performance, long lasting, safe and environmentally friendly roads to be constructed. Today, 94% of the 3.63 million km long coated roads in the USA and the 95% of the coated roads in Europe are asphalt coated, and the hot and cold mixture facilities for the light and heavy duty traffic roads and several surface coating types make the asphalt the most densely used material for road coating.

© 2007 İsfalt