Complex modulus and fatigue performances of bituminous mixtures with reclaimed asphalt pavement and a recycling agent of vegetable origin

The paper focuses on the investigation of the effects of a recycling agent on mechanical performances of bituminous mixtures produced with reclaimed asphalt pavement (RAP). Twenty-one different bituminous mixtures were produced and tested, using three distinct virgin binders (15/25, 35/50 and 70/100 penetration grades), with RAP contents varying from 0% to 60%. Seven of the mixtures were produced by adding a recycling agent of vegetable origin (its content was fixed equal to 3.5% by weight of the RAP binder). One of the mixtures is a 100% RAP mixture, produced only with RAP-extracted binder and aggregates issued from RAP material. Another one is a “perfect” mixture, produced by perfectly blending 70/100 base binder with 60% RAP-extracted binder and using this blend to coat virgin and RAP aggregates. Material properties were investigated using classical tests commonly performed by the road paving industry in Europe, in order to assess the impact of the addition of the recycling agent according to the current standard procedures. In particular, complex modulus |E*| (at 15°C and 10 Hz) and fatigue parameters 6 and 1/b (at 10°C and 25 Hz) were determined by means of two-point bending tests on trapezoidal samples. The addition of the recycling agent was observed to generally lower |E*| and improve fatigue performances of mixtures with a RAP content equal or greater than 40%.