Tjärhalter

Tjärhalter, often translated as "tar content" or "asphalt content," is a term primarily used in road construction and pavement engineering to describe the proportion of asphalt binder within a bituminous mixture. Asphalt binder, commonly known as bitumen, is the sticky, black, petroleum-based material that binds together the aggregate (stones, sand, and filler) in asphalt pavements.

The tjärhalter is typically expressed as a percentage by weight of the total mixture. This percentage is crucial for determining the performance characteristics of the asphalt. A higher tjärhalter generally leads to a more flexible pavement, better able to withstand cracking under stress. However, too much binder can result in a pavement that is susceptible to deformation, such as rutting, under heavy loads and high temperatures. Conversely, a lower tjärhalter can make the pavement more brittle and prone to cracking, especially in colder climates or under heavy traffic.

The optimal tjärhalter for a specific application is determined by various factors, including the type of aggregate used, the intended traffic volume and load, the climate, and the desired pavement properties. Pavement mix designs carefully balance the amount of asphalt binder with the aggregate to achieve a durable and long-lasting road surface. Engineers use laboratory testing and empirical data to establish the correct tjärhalter for different asphalt mixes, such as asphalt concrete or stone mastic asphalt. Monitoring and controlling the tjärhalter during the asphalt production process is a critical aspect of quality control in road construction.