Recycling of deteriorated asphalt pavements

Abstract

In most advanced countries, recycling of deteriorated asphalt pavements has become an established rehabilitation alternative. In this research, failed segment of Damman-Abu Hadriyah Expressway, which developed high severity alligator cracking, and weathering and raveling at km 140 was selected as a typical candidate pavement to study its adaptability to recycling. The study entailed laboratory evaluation fo reclaimed pavement samples with addition of virgin aggregate, virgin asphalt and a modifier to correct the existing deficiencies in the reclaimed pavement. Five types of modifiers, viz., mobilsol 120, dutrex 729 (UK), diesel oil, elemental sulphur, and modified sulphur (Chement 2000), based on their reported proven performance and local availability, were seleced to rejuvenae the aged aslpalt. Diesel oil had to be dropped subsequently due to its rapid volatilization characteristic resulting in much higher rate of hardening of asphalt blend as compared to virgin asphalt. Marshall mix design tests were conducted to determine the optimum quantity of modifier and virgin asphalt needed in each case. Dynamic tests, in terms of resilient modulus, fatigue cracking and vertical permanent deformation (to simulate rutting), were conducted on Marshall briquettes in an indirect tension mode. Split tensile strength was also determined under static loading. The test results showed that the recycled mixtures possessed characteristics similar to that of the virgin asphalt concrete mixture thus indicating a great potential for pavement recycling in field.