Proper bonding between the overlay and existing pavement is critical for long-term performance, as poor bonding creates a plane of weakness that can lead to delamination and premature failure. The bond strength depends on surface preparation quality, tack coat application, and installation techniques. Good bonding allows the overlay and existing pavement to act as a single structural unit, while poor bonding creates two separate layers that can move independently under traffic loads, causing cracking, rutting, and surface distress.