Potholes…no one likes them and we have to live with them until they are repaired.

How does a pothole form?

Potholes occur mostly in the winter with temperatures below freezing. Through traffic, streets are worn on the upper asphalt causing small cracks. Due to this, water penetrates into the roadway. In freezing temperatures, the water freezes and expands into the cracks, which are thereby increased. In the spring the sun melts the ice and it creates cavities. Since the ground is still frozen, the water cannot drain.

The pressure of the cars and trucks breaks the cavity. The asphalt begins to crumble and each additional car’s tires tear out new pieces of asphalt. The result: a pothole. Roads that drive increased trucks due to the high pressure (the pressure of a truck is as high as 500,000 cars in succession for the asphalt) are particularly vulnerable to potholes.

Here´s a sketch of how a pothole occurs:

Latest studies in Lyon, France have demonstrated that a big reason for potholes is the speed of which vehicles drive over it. With the origin of ground waves, small surface irregularities are sufficient, which can exist despite good rolling. The waves occur at critical speeds and are drifting slowly along the driving direction. In addition to the speed, the wheel is bouncing over these bumps and enlarging them. If and once a ground wave develops itself, others are resulting because of the carried away material.

Over the years the development for asphalt mixture and material temperature, paver and screed control, roller and compaction techniques go on and on. Maybe the following video can be a solution for the future, especially for bridges over water.

What do you think about this technology?

In Germany, the government and the underlying municipalities, rule and decide how much money will be invested to build new and rebuild existing roads per year.

How is this settled in your country?

Pavements - roads that are not ""tarred""

Even if it is still persistent in language use, roads in Germany are no longer "tarred" since the late 1970s. The late 1980s, tar and pitch mixing goods were outright banned. The reason? The manufacturing and installation of hot tar and pitch mix created unhealthy vapors.

Previously road tar or road pitch, mixtures of road tar and bitumen, as well as other tar and bituminous binders were used in various areas of road construction. They were used primarily as a binder for layers of the road superstructure (for example, so-called tar asphalt bituminous and tar asphalt concrete. While bitumen is extracted from oil, pitch comes from coal.

Today in the road construction, "bitumen" is used as a binder for hot mix and as a basis for contact spray ("bitumen emulsions"). From aggregates and bitumen asphalt mix is produced, which serves as a building material for asphalt layers at road superstructure.

In this respect, "tars" is a linguistic relic from the past, and has nothing to do with the production of a new layer of asphalt. Our streets are now "paved".