In what way does oxidation affect asphalt binders?

Oxidation significantly impacts asphalt binders by leading to hardening and a loss of flexibility. Over time, when asphalt is exposed to heat, air, and ultraviolet light, a chemical reaction occurs that causes the binder to oxidize. This process results in the formation of new compounds that can increase viscosity and create a stiffer material.

As a result of this hardening, the binder's ability to stretch and bend without cracking diminishes, which compromises the overall performance of the pavement. This loss of flexibility is critical because flexible binders are essential to accommodate the dynamics of traffic loads and temperature fluctuations; without adequate flexibility, the pavement is more susceptible to cracking and other forms of distress.

The other options do not accurately represent the effects of oxidation on asphalt binders. While oxidation can have various influences, the significant concern for asphalt pavement performance is primarily associated with hardening and loss of flexibility.