EFFECT OF EXTERNAL FACTORS ON PERMENENT DEFORMATION BEHAVIOR OF LOCAL ASPHALT PAVEMENTS

Permanent deformation (rutting) is considered one of the most important factors that reduces pavement life in roads network and highways in Iraq. In this paper, a laboratory investigation has been conducted to evaluate the effect of external factors on rutting of asphaltic mixture. The study was carried out using local materials for the surface layer. Three levels of temperature were examined namely, 40, 50, and 60 °C, in addition to three stresses intensities are 700N, 900N, and 1100N were investigated for wheel track test, and 10, 20, and 30 psi of repeated load were also tested. The results have cleared that the temperature and stress have a significant effect on the permanent deformation. Where mixtures resistance to rutting increases about 57.65% when temperature degree increases from 40 °C to 50 °C. Also, increasing load intensity from 700 to 900 N resulted in higher rutting values (about 40.75% increase has observed in term of WTT). Additionally, increasing temperature from 40 °C to 50 °C resulted in permanent strain and resilient strain increase by 84.49 % and 11.27 %, respectively. Also, increasing load intensity from 10 to 20 psi resulted in higher permanent strain and resilient strain values about 5.44 % and 27.94 %, respectively, for wearing layer. In term of uniaxial repeated load test, it has concluded that temperatures and stresses employed for design are relative high to reproduce the most unfavorable pavement conditions