[01] Saad Issa Sarsam, Department of Civil Engineering, College of Engineering, University of Baghdad, Baghdad, Iraq. [02] Mostafa Shaker Mahdi, Department of Civil Engineering, College of Engineering, University of Baghdad, Baghdad, Iraq.

Recycling of asphalt concrete for pavement construction is considered as a sustainable issue. The load repetition practiced by the pavement causes an initiation of micro cracks, while the self-healing phenomena of cracking can extend the service life of the pavement. In this investigation, aged asphalt concrete was obtained from the field and digested with carbon black and Styrene Butadiene Rubber (SBR) as recycling agents. Specimens of 102 mm diameter and 63.5 mm height of aged and recycled mixtures were prepared and compacted using Marshal method at 150°C. Specimens were subjected to repeated indirect tensile stresses ITS for 1000 load repetition through a heavier sine pulse of (0.1 sec. load duration and 0.9 sec. rest period) and constant stress level of 0.138 MPa with loading frequency of (60) cycles per minutes. Specimens were allowed to heal by external heating for 120 minutes under 60°C, then subjected to another 1000 ITS load repetition cycle. Dial gages and video capture have been used to monitor the deformation of the specimen under each load cycle. Then, the recorded data was analyzed for finding resilient modulus (Mr) and permanent strain. It was concluded that permanent deformation declines by (4, 4.7 and 20)% for aged and recycled mixtures with carbon black and SBR respectively after healing. The (Mr) at 25°C increases by (25, 30, and 20.5)% and (7.7, 5.8 and 5)% for (unconditioned and conditioned) aged and recycled mixtures with carbon black and SBR respectively after healing as compared with the similar mixture before healing.

Crack Healing, Recycling, Asphalt Concrete, Tensile, Repeated Load, Resilient Modulus, Deformation

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