päällystokerros

Päällystokerros refers to the top layer of a road surface, also known as the wearing course. This layer is the uppermost part of the asphalt or concrete pavement that directly interfaces with traffic and the environment. Its primary function is to provide a smooth, durable, and safe surface for vehicles to travel on.

The materials used in the päällystokerros are typically asphalt concrete or Portland cement concrete, chosen based on factors like expected traffic volume, climate conditions, and desired performance characteristics. Asphalt concrete wearing courses are commonly composed of aggregate (such as crushed stone or gravel) mixed with bitumen binder. The specific grading and type of aggregate, as well as the properties of the bitumen, are crucial for the layer's performance in terms of skid resistance, resistance to rutting, cracking, and weathering.

In concrete pavements, the päällystokerros might be a specific concrete mix designed for durability and abrasion resistance, or it could be a separate overlay material applied to the structural concrete layers. The design and construction of the päällystokerros are critical for the overall lifespan and performance of the road. Regular maintenance, including repairs and periodic resurfacing, is often necessary to ensure the päällystokerros continues to provide its intended functions effectively. A well-maintained päällystokerros contributes significantly to road safety by providing adequate friction and a comfortable ride.