Impact of Aging on Shear, Tensile Strength and Permanent Deformation of Superpave Asphalt Concrete

Age hardening is a major factor affecting the durability of asphalt paving materials. The material properties change with time as the asphalt cement becomes harder and the mixture becomes stiffer. There are two types of aging, short term aging (STA) at mixing and laying stage and long term aging (LTA) during service life of pavement. The influence of aging time on the indirect tensile strength, double punching shear, permanent deformation and fatigue life, have been investigated by employing the short term aging (STA) and long term aging (LTA). It was concluded that aging process exhibits good resistance to indirect tensile strength at the three temperatures (25 °C, 40 °C, 60 °C), while the shear increases, such rate of changes was (+4%, +22%, +22%, +87%) respectively for STA mixtures. On the other hand, the increment after LTA of mixtures is (+16%, +63%, +170%, +173%) respectively as compared with control mix. The permanent deformation decreases by 12% and 63% at STA and LTA respectively. An increment in asphalt content from (4.8 % to 5.3 %) causes 43% increase in permanent deformation (at 1000 cycle). A testing temperature change from 25 to 40 °C, leads to a permanent deformation increase by 113% at the same load repetition.