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Hot Recycling of Asphalt Rubber PavementsGreater environmental and economic benefits with the recycle of AR



Five binder-type mixes have been compared in the study about the possibility of using reclaimed asphalt-rubber pavement (rRAP) in the production of bituminous conglomerate. The mixes were of different nature: without reclaimed asphalt, with conventional reclaimed asphalt pavement (RAP), or with reclaimed asphalt rubber pavement (rRAP) and with or without the use of a rejuvenating additive.

The RAP added to the mixture of aggregates have been 30% more than what usually allowed by the technical specifications for the binder asphalt mixes. These extreme conditions were chosen in order to assess the recyclability of rRAP in new hot mix asphalt (HMA). The optimal dosage of bitumen was found to be similar for all mixes: close to 5% compared to the weight of the aggregates. As they contribute with a larger quantity of old bitumen, rRAP, however, require a smaller quantity of virgin raw bitumen compared to conventional RAP.

Moreover, rRAP determine minimal variations of the elastic module and they do not increment the Indirect Tensile Strength index (almost equivalent to the mix of reference) as conventional RAP do. The presence of the rejuvenating additive im- plies a reduction of the module. This is more evident in rRAP than in normal ones. The fatigue curves show that rRAP guarantee better resistance to imposed deformations thanks to the presence or rubber, which makes the mix more elastic.

On completion of the research activities, it is possible to state that rRAP can be used in the production of hot bituminous conglomerates. This does not penalise the mechanical and volumetric characteristics for uses up to 30% of the mass of the aggregates. Moreover, compared to conventional RAP and on equal terms of use, rRAP guarantee greater environmental and economic benefits, as they require lower amounts of new bitumen.