چكيده به لاتين
Abstract
Railway is one of the most important transportation system in the world. Asphalt offers good futures to be used in railway track construction (for both heavy loaded tracks and high-speed tracks). The use of asphalt materials instead of ballast aggregates in the railway construction provides positive contribution to bearing capacity of railway sub-structure. It improves both stability and durability of the railway structure and results in annual maintenance cost reduction when compared with the conversional ballasted track. Moreover, the use of asphalts helps to reduce train induced vibration and noise. However, one of the main concern in the use of asphalt instead of the ballast layer is its fatigue characteristics. Therefore, the asphalt-railway is usually designed on the basis of fatigue damage. Despite many studies on the fatigue behavior of asphalt, sufficient researches on fatigue behavior of asphalt mixes in the railway has not been made yet. In this research, the fortified math theory (such as the theory of viscoelastic continuum damage) was used in order to study of the behavior of asphalt mixes fatigue distress in the railways. For this purpose, 14 samples of asphalt modified with crumb rubber is used. In order to evaluate the effect of aging on the fatigue behavior, some of samples were aged by putting them in oven for 2 hours. Three experiments of creep compliance, constant strain rate and cyclic fatigue tests were carried out. The results obtained from the experiments and theory of viscoelastic continuum damage were used to illustrate the behavior Pseudo stiffness versus asphalt damage. It is shown that the coefficient of fitness function on the curve of Pseudo stiffness-damage is appropriate to be used in order to derive the fatigue life of asphalt mixes.
Keywords: asphalt mixture, viscoelastic continuum damage, creep compliance
