Mechanistic properties of the unaged and aged DGAMs

Al-Hadidy A.I. Rashed Abdullah M. Lecturer of Civil Engineering Department, MSc. Student, Civil Engineering Department University of Mosul, Mosul/Iraq, University of Mosul, Mosul/Iraq E-mail address abd_et76@yahoo.com. Tel. +9647710736289 , Abstract Short and long term aging were conducted on the dense graded asphalt mixtures (DGAMs) containing 40-50 penetration grade asphalt cement binders. The short term oven aging (STOA) was conducted on loose mixtures at temperature of 135 C for four hours and at temperature of 154 C for two hours, whereas, the long term oven aging (LTOA) was conducted at temperature of 85 C and at two periods of time between four and eight days. The performance tests includes: Marshall properties, indirect tensile strength at 25 and 60C, compressive strength at 25 and 60C, flexural strength at 0 and -10C, cohesion at 60C, tensile strength ratio, and index of retained strength were carried out on unaged and aged DGAM. A mechanistic-empirical design approach using BISAR program was adopted for estimating the improvement in service life of the pavement or reduction in thickness of DGAM and base layer for the same service life due to the aging of DGAM. The results showed that the STOA and LTOA increases: (1) resistance of DGAM against permanent deformation at high temperatures; (2) resistance to stripping phenomenon; (3) flexural strength at low temperatures; (4) traffic benefit ratio between 10 and 20%; and (5) reduces the thickness of the surface layer between 8 and 14%; and (6) the base thickness reduces between 35% and 55%.