Fracture Characterization of Stone Matrix Asphalt Mixtures Incorporating Reclaimed Asphalt Pavement and Rejuvenator

Abstract

Environmental, economic, and social benefits are encouraging the incorporation of reclaimed asphalt pavement (RAP) in stone matrix asphalt (SMA) mixtures. However, RAP-incorporating mixtures have higher stiffness, which leads to fracture failure. This research used semicircular bending (SCB) tests to evaluate the fracture characteristics, i.e., maximum tensile strength (TS), fracture energy (FE), and flexibility index (FI), of RAP-incorporating SMA mixtures with different rejuvenators. Four RAP contents (10%, 20%, 30%, and 40% by weight of the aggregate) and four different rejuvenators [waste vegetable oil (WVO), waste engine oil (WEO), waste grease (WG), and palm oil sludge (POS)] with four rejuvenator dosages (0%, 3%, 6%, and 9% by weight of binder) were used to prepare SMA mixtures. Fracture characteristics were analyzed using 100-mm-diameter Marshall specimens. Rejuvenated mixtures had about a 10% increase in the TS compared with nonrejuvenated mixtures. The WVO and WEO substantially increased the TS, FE, and FI values other two rejuvenators, whereas WG and POS provided no improvement. The incorporation of rejuvenator improved the fracture resistance and allowed up to 40% RAP content. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analyses were performed to examine the rejuvenators’ effectiveness at the microlevel. SEM images measured the level of activation of aged binder and the lubrication effect of different rejuvenators. In terms of fracture characterization, 30% RAP content along with 6% WVO was the best performing SMA mixture.