Improving the durability of asphalt mixtures with hydrated lime: Field results from highway A84

Although known for a long time, hydrated lime (HL) still attracts a strong technical interest as an asphalt additive. In this paper, recent field results obtained in France on highway A84 in Normandy after 5-years are presented. 5 sections with and without HL were constructed and followed. A thorough initial testing was performed, and completed by the extraction of specimens after 5-years in operation. The traffic was of order 15,000 vehicles/day with 15 % heavy trucks. The climate is oceanic with average minimum temperatures between 2−12 °C and maximum 7−23 °C. Rainfall averages 50−80 mm per month all year round. The mixtures were semi-dense Asphalt Concrete (French BBSG) with 15 % Reclaimed Asphalt Pavement (RAP). The experimental program included binder evaluation based on standard and advanced rheological and chemical testing, together with mixture tests such as retained strength after immersion, complex modulus and fatigue. For the first time, these results allow quantifying the impact of HL in the context of French mixtures. In addition, the negative effect of RAP on moisture resistance is highlighted and HL appeared as an efficient solution to minimize performance loss.