Influence of Healing Cycles and Asphalt Content on Resilient Modulus of Asphalt Concrete

Abstract

Asphalt concrete pavement is known to exhibit self-healing ability of micro-cracks under repeated loading with rest period and controlled environment. In this work, an attempt has been made to investigate the influence of healing cycles and asphalt content on resilient modulus of asphalt concrete. Asphalt concrete specimens of 100 mm diameter and 63 mm height have been prepared with optimum asphalt requirement and with additional 0.5% asphalt above and below the optimum. Specimens were tested for resilient modulus (Mr) under repeated tensile and shear stresses at 25°C. The loading cycle consists of load application for 0.1 sec followed by 0.9 sec of rest period. Specimens were allowed to heal by external temperature of 60°C for 120 min after each 1000 load repetitions, then subjected to another load repetition cycles. It was concluded that permanent deformation decreases as the healing cycles increase. Mr under indirect tensile stress (ITS) increases by (33.4, 100), 100, and (25, 150)% after one and two healing cycles respectively as compared with control mix for mixes with 4.4, 4.9, and 5.4% asphalt content, while Mr under punching shear stress (PSS) decreases by (18.3, 30.7) and (7.8, 25.2)% after one and two healing cycles respectively for mixes of 4.9 and 5.4% asphalt content as compared to 4.4% asphalt content mix. The variation of asphalt content has significantly reduced the permanent deformation by a range of 3–19 and 13–43% for ITS and PSS testing modes respectively. Mr under ITS is 2–3 folds higher among 50 and 500 load repetitions.