What is Asphalt

7/30/2019 What is Asphalt

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By: Engr Muhammad Bilal Israr Page 1

What is Asphalt?

Asphalt is a mixture of aggregates, binder and filler, used for constructing and maintaining all

kind of roads, parking areas but also play- and sport areas. Aggregates used for asphalt mixtures

could be crushed rock, sand, gravel or slags. In order to bind the aggregates into a cohesivemixture a binder is used. Most commonly, bitumen is used as a binder. An average asphalt

pavement consists of the road structure above the formation level which includes unbound and

bituminous-bound materials. This gives the pavement the ability to distribute the loads of thetraffic before it arrives at the formation level. Normally, pavements are made of different layers:

Uses of Asphalt:

Although asphalt is mainly used for paving roads, it can also be used for various other purposes.

The versatility of asphalt makes it such a widely used material. Among others, it can be found in

the following sectors:

Transportation (e.g. roads, railway beds or airport runways, taxiways, etc.),

Recreation (playgrounds, bicycle paths, running tracks, tennis courts...)

Agriculture (barn floors, greenhouse floors...)

Industrial (ports, landfill caps, work sites...)

Building construction (floorings...)


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How is Asphalt produced:

Asphalt can be produced in a fixed plant or even in a mobile mixing plant. It is possible to

produce up to 800 tons per hour. The average production temperature of hot mix asphalt is

between 150 and 190C, which depends however on the mixture produced (see below).

Different kinds of Asphalt:

To be able to provide the best performance to different sectors, a large variety of asphalt mixes

can be offered. Due to the different requirements e.g. a road needs to fulfill (high traffic, toughweather conditions etc) the respective mix used needs to have an sufficient stiffness and

resistance to deformation in order to cope with the applied pressure from vehicle wheels on the

one hand, yet on the other hand, the need to have an adequate flexural strength to resist cracking

caused by the varying pressures exerted on them. Moreover, good workability during application

is essential in order to ensure that they can be fully compacted to achieve optimum durability.

Hot Mixo Hot mixes are produced at a temperature between 150 and 190 C.o Depending on the usage, a different asphalt mixture can be used.

Porous Asphalt Stone Mastic Asphalt Mastic Asphalt Hot Rolled Asphalt Soft Asphalt Asphalt Concrete

Asphalt Concrete for very thin layers Asphalt Concrete for ultra thin layers Double layered Porous Asphalt

o Warm Mix A typical WMA is produced at a temperature around 20 - 40 C lower

than an equivalent Hot Mix Asphalt. Less energy is involved and, during

the paving operations, the temperature in the mix is lower, resulting in

improved working conditions for the crew and an earlier opening of theroad.

o Cold Mix Cold mixes are produced without heating the aggregate. This is only

possible, due to the use of a specific bitumen emulsion which breaks eitherduring compaction or during mixing. After breaking, the emulsion coats

the aggregate and over time, increases its strengths. Cold mixes are

particularly recommendable for lightly trafficked roads.


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Did you know that...

...asphalt is sometimes referred to as a flexible pavement. This is due to its ability to largely

resist the stress imposed by slight settlements of the subgrade without cracking.

...asphalt is the predominant material used for road construction and maintaining the road

network in Europe?

...25% of the total world asphalt production takes place in Europe?

...the average amount of bitumen used in asphalt is 5% by weight?

...Europe has over 4.000 asphalt production sides and over 10.000 companies are involved inthe asphalt production and or laying?

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What is Asphalt