What happens to asphalt binder when exposed to air for a long time?

• A. It becomes more flexible
• B. It becomes less flexible
• C. It does not change
• D. It becomes volatile

Answer: (B)

When asphalt binder is exposed to air for an extended period, a process known as oxidation occurs. During oxidation, the exposure to oxygen leads to the hardening of the asphalt binder. This hardening results in a chemical change, causing the binder to lose its flexibility. As a consequence, the material becomes more brittle and less able to accommodate the stresses and movements it would typically experience in pavement applications.

This reduction in flexibility can adversely affect the performance of asphalt pavements, making them more prone to cracking and other forms of damage, especially under temperature variations and loading conditions. Therefore, the correct understanding reflects that with prolonged exposure to air, the asphalt binder indeed becomes less flexible, leading to a decrease in its overall performance in paving applications.