Evaluation of fatigue cracking of hot-mix asphalts containing recycled concrete aggregates coated with waste plastic bottles using thermodynamic parameters

Coarse recycled concrete aggregates (CRCAs) were used as substitutes in asphalt mixtures. These aggregates have a layer of porous cement mortar on their surfaces that impairs their physical and mechanical properties. Therefore, their surfaces were coated with waste plastic bottles to improve their quality. Fatigue cracking, as a critical failure, in asphalt mixtures containing 0, 15, 30, and 50% coarse recycled concrete aggregate was evaluated using the indirect tensile fatigue test in wet and dry conditions. Also, the adhesion of mixture ingredients (bitumen and aggregates) to each other was determined using the sessile drop test based on the surface free energy concept. According to the results, the asphalt mixes containing CRCA had a higher optimum bitumen content compared to the control mixture. The modified asphalt mixtures had a shorter fatigue life in wet and dry conditions. Furthermore, moisture reduced the fatigue resistance of the control and modified asphalt mixtures, and this rate of decline was greater in the mixtures containing CRCA due to their high absorption.