Road Surface

The road surface is visible and can be also perceived with other senses. Who hasn’t stepped on an asphalt road barefoot in summer? While driving a car we always notice the irregularities in the surface, as well as potholes in spring. The road surface may be made of gravel, cobble stones, concrete, blacktop or bituminous concrete. Road surfacing materials other than gravel are non-volatile, but all are subject to wear. Cobblestones and concrete are the most durable. Next are bituminous concrete and various blacktop mixtures.

In Estonia, the first test stretch made of bituminous concrete was a few hundred meters long and was constructed in Tallinn in 1924. One year later concrete was tested as well. A more widespread practice was to lay cobblestone paving at city and town access roads, a practice which was later abandoned, as when speed increased, cobblestones were not suitable for car traffic. As constructing concrete and bituminous concrete roads was very expensive, it did not develop further from the test stretches.

After World War II, the most popular road surface material in Estonia was a strange mixture of bitumen and gravel called blacktop. However, as was soon discovered, blacktop does not last in our climate without a protective top layer, and the roads were resurfaced. Bitumen and crushed stone were used for this.

Since the 1970s, the most dominant surfacing material on new roads in Estonia is bituminous concrete. On highways with heavy traffic the road surface may consist of many layers of bituminous concrete with different durability. The visible and perceivable top layer is called the wearing course.