Describe the impact of aggregate type on asphalt mix performance.

The impact of aggregate type on asphalt mix performance is significant and multifaceted. Different types of aggregates can influence a variety of performance characteristics that are critical for the durability and safety of pavement.

Durability is affected because the hardness and wear resistance of the aggregate contribute to the overall longevity of the asphalt mix. For instance, aggregates that are too soft can break down under vehicle loads and weather conditions, leading to premature failure of the pavement.

Skid resistance, which is vital for vehicle safety, is also dependent on the type of aggregate used. Textured and rough aggregates can provide better traction, reducing the likelihood of vehicle skidding in wet conditions. The shape and angularity of the aggregate particles influence how well they interlock in the asphalt mix, further impacting skid resistance.

Thermal expansion characteristics can be tied to the mineral composition of the aggregates. Different aggregate types may expand and contract differently under temperature changes, which can lead to cracking and deformation in the asphalt mix over time if not properly managed.

Ultimately, the correct selection of aggregate type is crucial in designing asphalt mixes that meet specific performance specifications for various applications, ensuring that the pavement remains safe, durable, and functional throughout its service life.