What happens to asphalt binder when exposed to air over time?

When asphalt binder is exposed to air over time, it undergoes a process known as oxidation. This exposure leads to the formation of new compounds within the binder as oxygen from the air chemically reacts with the asphalt. As a result, the binder stiffens and becomes less flexible. This increased stiffness can negatively impact the performance of the asphalt mix, making it more susceptible to cracking and reducing its overall durability.

The aging process can also lead to the loss of volatile components in the binder, further contributing to this change in properties. Therefore, the ability of the asphalt to adapt to thermal and traffic stresses diminishes as it ages, highlighting the importance of using appropriate materials and maintenance strategies in pavement construction. Understanding this aspect of asphalt behavior is crucial for ensuring long-lasting road infrastructures.