What is asphalt? – Let’s find out all about it.
What is Asphalt? Asphalt is a natural or artificial multicomponent material based on surface (formed when coming to the surface of the earth) or oil (obtained as a result of oil refining and subsequent processing of residual tar in the sediment) bitumen containing mineral fillers – gravel, crushed stone of various rocks, sand.
In fact, the application of the term “asphalt” to road asphalt mixtures is incorrect. The content of asphalt as a mixture of bitumen in the total mass is several times less and depends on the grade of the material.
The beginning of using asphalt for road construction
The first mentions of using natural asphalt for road construction date back to the 16th century and South America. The production of artificial cast asphalt mixtures appeared in the United States only at the end of the 19th century; bitumen-mineral compositions came to the streets of Europe a little earlier – in 1830-40. paved sidewalks and carriageways of cities in France, Austria, Great Britain, and Russia began to be replaced by asphalt pavements.
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The first trial and larger-scale asphalting experiment was carried out in St. Petersburg, but only by the 80s. The new road material spread to other major cities. At the same time, their own plant was not built in Russia immediately – for three decades; the then progressive product was bought abroad.
America was again the pioneer in mechanized packing. It was here that the tarmac was first used to build the road, from which hot bitumen was poured.
Composition of natural and artificial asphalt
Natural asphalt is mined from rare deposits – Peach Lake in Trinidad, the Dead Sea in Israel, the province of Alberta in Canada, the Orinoco Belt in Venezuela, the US states, Iran, and Cuba. The composition includes a mixture of bitumen with a content of up to 70%, inorganic inclusions, and organic compounds.
Artificial asphalt mixes consist of two main components. Viscous, low-viscosity, or liquid petroleum, modified bitumen, and PBB (polymer-bitumen binders) act as a binder. Crushed stone/gravel of different fractions from 5-10 mm to 20-40 mm, sand and mineral powder are used as fillers to improve strength, viscosity, and fill voids.
Asphalt concrete is a monolithic road surface obtained by laying and compacting an asphalt concrete mixture.
The classification of asphalt concrete mixtures is carried out according to residual porosity, type of mineral materials, their fraction and percentage, bitumen binder, and laying temperature.
Certain types of asphalt concrete mixtures
In addition to traditional and commonly used asphalt concrete mixtures, there are more progressive road materials that differ from the first in composition and laying conditions.
- Cast asphalt mixes with increased content of bitumen and mineral powder.
- Polymer- asphalt-concrete mixtures with the addition of polymers (elastomers).
- Color hot and cold mixtures with coloring pigments.
- Stekloasphaltobe ton mixtures with the inclusion of glass breakage.
- Rubber-asphalt-concrete and rubber drainage mixtures with crumb rubber and polymer additives.
- Sulfur-asphalt-concrete mixtures with the presence of technical sulfur.
Each type of material has a specific field of application due to the characteristics and performance, and properties of the resulting coating.