Asphalt Concrete

Asphalt is a black sticky semi solid substance which is formed as residual product in the distillation of coal or petroleum. The sticky nature of asphalt makes it an ideal component to be used as a binding agent for aggregate particles during road construction. Asphalt concrete is the name given to this particular composite material formed by asphalt and aggregate particles like stone, sand and other such granular particles. Asphalt concrete is used throughout the world to construct roads and the trend looks to continue in the future as well in spite of certain problems of these roads.

Composition and Properties

Asphalt concrete is basically composed by the asphalt and the aggregate materials with the 95% of the later being mixed with 5% of the former. There are proper guide lines for selection of the aggregate materials such as the materials being non-plastic, reducing the amount of clay in the mixture, limiting the amount of natural sand in the mixture depending upon the type of road the asphalt concrete is to be applied on, etc. The properties of asphalt concrete that is the tire wear, braking efficiency etc. of automobiles and other properties depend on the materials present in the aggregate mostly.

 

The asphalt and concrete can be mixed in different ways with the major ways being:

 

 

Cut-back, Mastic and regular are the other types. It is usually thought of to be recyclable although the recycled material finds little use other than perhaps being the base material.

Advantages and Disadvantages

Asphalt concrete has various advantages as compared to other materials. It is cheap material and the installation can be done at a low price as well. It is easy to maintain as the cracks can be patched without much hassle. But there are certain disadvantages to it. In certain highways under the heat of the sun, asphalt tends to become softer and thus making asphalt concrete roads and highways more liable to cracks under increased traffic loads.