Laboratory Evaluation of High Asphalt Binder Replacement with Recycled Asphalt Shingles (ras) for a Low N-design Asphalt Mixture

This study investigated the effect of high asphalt binder replacement for a low N-design asphalt mixture including RAP and RAS on performance indicators such as permanent deformation, fracture, fatigue potentials, and stiffness, was studied. An experimental program included complex modulus, fracture, overlay reflective cracking resistance, wheel track permanent deformations, and push-pull fatigue tests. The asphalt binder replacement, combinations of RAS and RAP asphalt binder, levels in the mix were in a range of 43 to 64%. According to the results obtained from the experimental program, permanent deformation resistance of the mixtures was improved in the presence of RAS. Fracture tests at low temperature did not reveal any significant difference between the specimens prepared at varying percentages of asphalt binder replacement. Fatigue potential of mixtures increased with increasing RAS content and asphalt binder replacement. The specimens prepared with 2.5% RAS and PG 46-34 showed the best fatigue performance. The impact of asphalt binder bumping was highlighted by the results of all tests. The improvement in fatigue life and fracture energy was noticeable when the asphalt binder type was changed from PG 58-28 to PG 46-34 at the highest asphalt binder replacement level. The results showed that complex modulus test results can provide crucial information about the mix viscoelastic properties such as relaxation potential and long-term stiffness that can be used, along with fracture tests, to evaluate mix brittleness at relatively high asphalt binder replacement levels.