Asphalt modifiers are typically applied during the mixing process of asphalt or bitumen. They can be introduced as solid, liquid, or powder forms, depending on the type of modifier used. The modifier is blended with the asphalt binder at elevated temperatures to ensure proper dispersion and interaction. This process enhances the performance characteristics of the asphalt, improving properties such as elasticity, temperature resistance, and durability, ultimately leading to a more resilient pavement.