Comparative Performance Evaluation of Hydrated Lime in Asphalt Mixtures Using Dry and Wet Incorporation Methods

This study investigates the influence of hydrated lime (HL) incorporation methods on the performance of asphalt mixtures by directly comparing equivalent hydrated lime contents introduced through dry and wet incorporation techniques. In the conventional dry method (DM), HL was incorporated at dosages of 1.5% and 2% as a mineral filler replacement, whereas in the wet method (WM), HL was added to the asphalt binder at dosages of 5%, 7%, 10%, and 30% by binder weight. The experimental program was designed to distinguish the influence of the incorporation method from that of hydrated lime dosage by comparing approximately equivalent HL contents. In particular, 1.5% HL by mixture weight is approximately equivalent to 30% HL by binder weight, enabling a direct comparison between the dry and wet incorporation methods. The asphalt mixtures were evaluated through complementary laboratory performance tests, including moisture susceptibility, low-temperature cracking performance, and rutting resistance. Stripping was evaluated with both Marshall Immersion (MI) and Modified Lottman (ML) tests, and both methods are comparatively examined in terms of stripping. When stability/flow ratios are evaluated for stripping, values above 90% drop to 60%. Much lower Marshall stability/flow ratios are obtained compared to Marshall Stability ratios. AASHTO T283 water damage assessment ratios are lower than those of the Marshall ratios. It is observed that the rutting and stripping resistance of the mixtures is improved with the addition of HL. The 1.5% HL modification showed the highest performance in terms of both stripping and rutting. The experimental results suggest that hydrated lime may contribute to a more homogeneous mastic structure, resulting in improved consistency of the measured performance properties. HL offers comparable, acceptable, and superior performance in all additive options and ratios, in terms of performance issues. AASHTO T283 and HWTT tests, in particular, clearly demonstrate this. However, fatigue-related studies should be conducted to assess actual long-term performance issues.