ASPHALT-PAVER

A asphalt- paver is a piece of construction equipment used to lay asphalt on roads, bridges, parking lots and other such places. It lays the asphalt flat and provides minor compaction before it is compacted by a roller.

The asphalt is added from a dump truck or a material transfer unit into the paver’s hopper. The conveyor then carries the asphalt from the hopper to the auger. The auger places a stockpile of material in front of the screed. The screed takes the stockpile of material and spreads it over the width of the road and provides initial compaction.

The paver should provide a smooth uniform surface behind the screed. In order to provide a smooth surface a free floating screed is used. It is towed at the end of a long arm which reduces the base topology effect on the final surface. The height of the screed is controlled by a number of factors including the attack angle of the screed, weight and vibration of the screed, the material head and the towing force.

To conform to the elevation changes for the final grade of the road modern pavers use automatic screed controls, which generally control the screed’s angle of attack from information gathered from a grade sensor. Additional controls are used to correct the slope, crown or superelevation of the finished pavement.

In order to provide a smooth surface the paver should proceed at a constant speed and have a consistent stockpile of material in front of the screed. Increase in material stockpile or paver speed will cause the screed to rise resulting in more asphalt being placed therefore a thicker mat of asphalt and an uneven final surface. Alternatively a decrease in material or a drop in speed will cause the screed to fall and the mat to be thinner. The need for constant speed and material supply is one of the reasons for using a material transfer unit in combination with a paver. A material transfer unit allows for constant material feed to the paver without contact, providing a better end surface. When a dump truck is used to fill the hopper of the paver, it can make contact with the paver or cause it to change speed and affect the screed height.

SINGLE DRUM ROLLER

Small and medium-sized single drum rollers weighing between 6 and 9 tonnes are distinguished by the width of the drum min. 1,4 to max 1,7 m. They are equipped with two or more vibrations and are suitable for small / medium jobs in urban and industrial areas. They can be equipped with padfoot drum (or padfoot shells that apply to the smooth drum) to compact the clay soils.

Medium-to-large single drum rollers weighing from 10 to 24 tons are distinguished by the width of the drum from min 2 to 2.2m. They are generally equipped with many vibrations and for heavier, even specific options for compaction tests. They are suitable for large freeways detected. They can be equipped with padfoot drum (or padfoot shells that apply to the smooth drum) to compact the clay soils.

SOIL STABILAZER

A soil stabiliser is a construction vehicle with a powered metal drum that has rows of mixing blades or paddles. It makes soil cement by blending soil, a binder agent (usually Portland cement or lime) and water together with paddles in the mixing chamber instead of a concrete mixer and usually does not cut or mill hard or very thick asphalt or concrete. Modern soil stabilisers are more powerful and often use carbide tips instead of paddles. Some are called single pass soil stabilizers because they can make soil cement in one pass where some of these machines take up to four passes. In this way most soil stabilisers have become much more like road recyclers where they can also blend the old road surface in the mixture.