Bonding characteristics between asphalt concrete layers have been a major concern for decades, as poor adhesion can lead to premature pavement distress, including cracking and fatigue. Hence, this study investigates the individual and interactive effects of temperature, tack coat application rate, confinement load, aggregate interlock, surface preheating, and geocomposite reinforcement on interlayer shear strength. The results showed that temperature is the most detrimental factor, reducing the strength overall by more than 2.5 times as it increased from 10°C to 40°C. Meanwhile, confinement load and aggregate interlock are the most important contributors to strength. Applying a 100 kPa confinement pressure boosted average strength by 60%, and aggregate interlock increased strength by 28% at high temperatures. Furthermore, statistical analysis revealed that surface preheating has no significant impact on the final strength. Importantly, critical interactions between confinement load and tack coat rate, as well as a negative interaction between aggregate interlock and the geocomposite, were recognised. Specifically, while aggregate interlock significantly increased strength by 28% at 40°C, the addition of geocomposites introduced a negative interaction, reducing the shear strength by approximately 17%. This finding quantifies the trade-off, demonstrating that geocomposites can partially negate the mechanical benefits of interlock. These results provide a robust framework for optimising pavement design by prioritising synergistic factor combinations.