International Journal of Scientific Research in Knowledge, 2(10), pp. 487-496, 2014 Available online at http://www.ijsrpub.com/ijsrk ISSN: 2322-4541; ©2014; Author(s) retain the copyright of this article http://dx.doi.org/10.12983/ijsrk-2014-p0487-0496 487 Full Length Research Paper Impact of Aging on Shear, Tensile Strength and Permanent Deformation of Superpave Asphalt Concrete Saad Issa Sarsam*, Ali Hussein Alwan Department of Civil Engineering, College of Engineering, University of Baghdad, Iraq *Corresponding Author: Email: saadisasarsam@coeng.uobaghdad.edu.iq Received 30 August 2014; Accepted 03 October 2014 Abstract. 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. Keywords: aging; tensile strength; shear strength, permanent deformation 1. INTRODUCTION The asphalt paving mixture is normally subjected to various detrimental types of distresses during its service life. Durable pavement is one, which is able to stand under such distresses for a long period without significant deterioration. In aging, the material properties change with time as the asphalt cement becomes harder and the mixture becomes stiffer due to oxidation and loss of volatiles, (Sarsam, 2007). Meanwhile most of the available distress prediction models are not considering the effects of aging on performance of asphalt pavement, (Sarsam and Al- Sadik, 2014). Petersen (1984) suggested the fundamental factors which causes hardening in asphalt materials; the loss of oily components of bitumen by volatility or absorption by mineral aggregate, the changes in chemical composition as chemical molecules of bitumen react with oxygen (oxidation) and molecular structuring causing thixotropic effects (steric hardening). Oxidation is the phenomenon when chemical molecules in bitumen are oxidized by oxygen in the atmosphere and form polar groups containing oxygen, for instance, hydroxyl, carbonyl and carboxylic groups, (Read and Whiteoak, 2003). Ageing is also due to the loss of volatiles in bitumen. Oily proportion of bitumen primarily volatizes due to high temperature. In addition, the loss of volatiles is also attributed to long-term exposure of asphalt to the environment. In addition, depending on the mineralogy of aggregate, oily component is also absorbed by porosity when bitumen is in contact with aggregate. However, the hardening due to this phenomenon is not considerable compared to ageing by oxidation, (Sarsam and Al-Sadik, 2014). Nguyen (2009) studied many factors affecting the ageing mechanism such as, air void content, temperature, and production. Characteristics before and after ageing are determined by resilient modulus and indirect tensile tests. Othman et al. (1995) and Raad et al. (2001) performed laboratory beam fatigue studies with aged asphalt mixtures at different temperatures, intermediate to low. Testing results indicate that aging typically reduces the fatigue resistance, and the effects of aging are more severe at low temperatures than at intermediate temperatures. It can be inferred that the more compatible characteristics of aging at low temperatures are due to increasing brittleness and reduced viscous nature during aging. Daniel et al. (1998) investigated the effects of aging on fatigue behavior of asphalt aggregate mixtures by monitoring