Selasa, 25 Juli 2017

Background, Type, Function, and Manufacturing Process of Asphalt

Photo by Ralph Bolliger on Unsplash - 

Background Asphalt

The history of the use of asphalt began thousands of years BC by the Sumerians and Mesopotamia.

They use bitumen (often called bitumen) as a sealing layer for bathtubs and pools of water in the palaces and temples.
  • John Metcalf
  • John Loudon Mc Adam
  • Deploying hot mix asphalt in the 18th century.
  • Dumptruck (early 19th century) was pouring hot mix.
  • Asphalt Sprayer (early 19th century)
  • Tandem Roller (stoom) early 19th century
Types of Asphalt

Natural Asphalt

a. Natural asphalt can be distinguished :
  • Asphalt mountain (Rock Asphalt). Example: Asphalt of Buton Island
  • Asphalt lake (Lake Asphalt). Example: Asphalt of Bermudus Trinidat
b. Based on its purity as follows :
  • Pure and nearly pure (Bermuda Lake Asphalt)
  • Mixed with minerals in Pylau Buton, Asphalt mountain (Rock Asphalt). Example: Asphalt of Buton island, Trinidat, France and Switzerland
Asphalt artificial

This type made from petroleum processing. Petroleum asphalt with the base material can be distinguished:
  • Asphalt Hard
  • Liquid asphalt
Asphalt Emulsion

Asphalt emulsion is a mixture of bitumen with water and emulsifiers based on electrical discharges that contain bitumen emulsion.

Function of Asphalt
  • Binders, providing a strong bond between the asphalt and aggregate and the asphalt itself and adding stability or provide some sort of cushion between the rocks.
  • Fillers, fill the voids between the grains and pore-bitir existing aggregate of the aggregate itself.
  • Cover the road surface to dust and make a waterproof road surface.
Raw Material

The raw material used in modern asphalt manufacturing is petroleum, which is a naturally occurring liquid bitumen.

Asphalt is a natural constituent of petroleum, and there are crude oils which are almost entirely asphalt.

Oil wells supply the crude petroleum to the oil refineries, where it is separated into its various components or fractions.

Manufacturing Process

1. Distilling the crude

The refining process starts by piping the crude petroleum from a storage tank into a heat exchanger or tube heater where its temperature is rapidly raised for initial distillation

2. Cutting back

Asphalt may next be blended or "cut back" with a volatile substance, resulting in a product that is soft and workable at a lower temperature than pure asphalt cement.

3. Emulsifying

To emulsify, the asphalt cement is ground into globules 5 to 10 microns and smaller (one micron is equal to one millionth of a meter).

This is mixed with water. An emulsifying agent is added, which reduces the tendency of the asphalt and water to separate.

4. Pulverizing

Asphalt may also be pulverized to produce a powdered asphalt.

5. Air Blowing

This process produces a material that softens at a higher temperature than paving asphalts. The asphalt is heated to 500°F (260°C).

Then air is bubbled through it for one to 4.5 hours. When cooled, the asphalt remains liquid.

6. Asphalt Paving Mixture

There are two types of asphalt mixes: hot-mix and cold-mix. 

7. Quality control

The quality of asphalt cement is affected by the inherent properties of the petroleum crude oil from which it was produced.

For engineering and construction purposes, there are three important factors to consider: consistency, also called the viscosity or the degree of fluidity of asphalt at a particular temperature, purity, and safety.

Byproducts or Waste

Environmental protection laws have developed stringent codes limiting water flows and particulate and smoke emissions from oil refineries and asphalt processing plants.

Not only dust but sulfur dioxides, smoke, and many other emissions must be rigorously controlled.

Handling of Waste
  • Hot-mix recycling, where reclaimed materials are combined with new materials in a central plant to produce hot-mix paving mixtures
  • Cold-mix recycling, where reclaimed materials are combined with new materials either onsite or at a central plant to produce cold-mix base materials
  • Surface recycling, a process in which the old asphalt surface pavement is heated in place, scraped down or "scarified," remixed, relaid, and rolled.
*Sumber: Sosna Sri R.
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