The action of hydrated lime on the durability of energy-efficient asphalt concrete

The main priority in road construction is to reduce the energy consumption in the production of mineral-asphalt mixtures used for the upper layers of pavement structures. The most effective technology in this regard is the use of water-foamed bitumen. It allows for the production of water-foamed binders from which asphalt mixtures are made using a “half warm mix” technology at temperatures 40 °C to 60 °C lower than traditional production. In the research, AC 8S asphalt concrete was used, made with 50/70 bitumen. The proper foaming of bitumen 50/70 were achieved by using a surface active agent. Hydrated lime was also used as a substitute for part of the mineral filler in the asphalt mixture. The aim of the research was to determine the operational durability parameters of asphalt concrete, such as intermediate tensile strength in the temperature range from -10 °C to +40 °C, and resistance to permanent deformations. Using Harrington’s utility function, the optimal content of hydrated lime and foamed asphalt was determined based on the required durability of asphalt concrete. The obtained effect is a consequence of the synergy between hydrated lime and foamed bitumen in the AC 8S mixture made using the “half warm mix” technology.