Asphalt Pavers and Their Mechanisms

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As the name suggests, asphalt pavers are construction equipment used to lay asphalt on roadways, parking lot, or other outdoor surfaces. Asphalt mixture is made from a crude oil by-product mixed with gravel and other aggregate materials. There are two main kinds of asphalt pavers. The first one is the one that is towed by a dump truck or tractor, or is also called compact unit asphalt pavers. The second one is the self-propelled asphalt pavers.

Compact unit is usually used for small paving jobs like in the parking lots. It works well for narrow areas but do not have the power to cover wide sections of roadway in just a single pass. It only has 3-20 horsepower.

Self-propelled asphalt pavers are ideal for large projects. Its horsepower ranges from 100 to 250. These units are composed of two major parts: the tractor and the screed.

  • The tractor is used to maneuver and move the paver forward, and to distribute the asphalt. It is composed of the engine, distribution augers, hydraulic drives and controls, feeder conveyors, drive wheels or tracks, and a hopper for receiving the asphalt. Dump trucks fill up the paver with aggregate materials before the job begins. Heating and mixing mechanisms in the paver help keep the asphalt blended and at the right temperature.
  • The screed assists in shaping and leveling the surface in preparation for the rolling machine. It contains vibration components and complex sensors that allow it to adjust itself, keeping the roadway as smooth and compressed as possible. The operator can widen or narrow the screed automatically by using the controls on the tractor. The screed may be positioned in front of the vehicle when dealing with smaller asphalt pavers. This provides better control and usage. However, when dealing with larger projects, the screed is pulled behind the paver as this permit wider area to be paved easily.

Design

Manufacturers of asphalt pavers usually offer a number of sizes and models. Large self-propelled pavers are usually 19-23 feet long, 10 feet wide, and 10 feet high. They weigh at about 20,000-40,000 pounds depending on engine size, hopper capacity, and kind of drive system. Paving width standard size is 8-12 feet up to a maximum width of 40 feet and paving thickness is up to a maximum of 6-12 inches on a single pass. The usual rate of asphalt placement is 100-300 ft/min.

The components of an asphalt paver are almost completely made of steel. The tractor body is made-up from heavy-gauge steel plate. The distribution augers are made of cast nickel-hard steel. The screed is made-up from steel tubing, channel, and plate. The feeder conveyor is made of flight bars.

How does it work?

Before the job is done, a dump truck fills up the paver’s hopper with asphalt. A tractor propels the paver forward, while the feeder conveyors are used to push the asphalt towards the back of the machine. The distribution augers spread the asphalt outward to a certain width decided by the operator. Each auger has free control of the asphalt on either side of the paver. Screed unit is heated; it levels and partially compresses the asphalt. A roller (separate machine) follows the paver to complete the compaction of the asphalt.