Why is segregation considered a problem in asphalt paving?

Segregation in asphalt paving refers to the separation of aggregate particles of different sizes within the asphalt mixture. This phenomenon can lead to weak spots within the pavement, as the materials do not mix uniformly, resulting in areas that contain either too many fine particles or an excess of larger aggregates. When segregation occurs, these weak spots can manifest as raveling, cracking, or lateral displacement of the asphalt during its lifespan.

The presence of weak spots directly affects the durability of the pavement. Areas that are inconsistent in composition may not withstand the same stresses as uniformly mixed asphalt, causing premature failure. Reduced durability translates to a shorter lifespan for the pavement, necessitating costly repairs and maintenance more frequently than would be required for a properly mixed asphalt surface. Hence, understanding and preventing segregation is crucial for achieving optimal performance and longevity of asphalt pavements.