Laboratory study of the effect of RAP conditioning on the mechanical properties of hot mix asphalt containing RAP

This paper evaluates the effect of reclaimed asphalt pavement (RAP) laboratory conditioning on the rheological properties of recycled hot-mix asphalt. Four different conditioning processes were used on a single RAP source before mixing: unheated RAP, RAP heated at 110 °C in a microwave, RAP heated in a covered pan at 110 °C in a draft oven, and RAP heated in a non-covered pan at 110 °C in a draft oven. Dense graded 20 mm HMA was designed using a PG 64-28 binder and mixed with 25 % of the four different conditioned RAPs. Thermal stress restrained specimen test (TSRST) and complex modulus test were used to characterize RAP conditioning effect. Test results showed that the complex modulus of the four mixes has no different rheological behaviour, and did not affect TSRST results as much.