Hot recycling of reclaimed asphalt using a bio-based additive

Hot recycling of reclaimed asphalt (RA) has increasing interest worldwide due to economical and environmental benefits. In particular, the use of RA in place of virgin aggregates reduces of aggregate supply and disposal of RA. Moreover, the hot recycling process allows reusing the aged bitumen from the RA, implying a reduction of the required amount of new bitumen. However, the ageing process, which occurs from the production throughout the service life of the pavement, affects physical and chemical properties of bitumen, determining its hardening. For this reason, when high amounts of RA has to be reused (more than 20% by aggregate weight), the use of specific additives is strongly recommended in order to reach the desired bitumen properties and consequently to produce an asphalt concrete (AC) with high performance. This experimental project focused on the use of a bio-based additive (A) for the production of an AC for binder course with a high amount of RA. The experimental program consisted of two main phases: the first phase dealt with the mix design of three mixtures containing respectively no RA, 40% of RA, 40% of RA treated with A; the second phase aimed at producing and laying down in a trial section selected mixtures for the validation of the full-scale hot recycling process.