Damage Theory Applied to Flexural Fatigue Tests on Conventional and Asphalt Rubber Hot Mixes

Abstract

Application of the Continuum Damage Theory (CDT) to evaluate the evolution of internal damage in Hot Mix Asphalt (HMA) is investigated in this paper. The CDT leads to the formulation of a characteristic curve relating normalized pseudo-stiffness and the internal damage variable, and this curve is supposed to be unique for each material. The uniqueness of the characteristic curve was investigated in this paper by performing fatigue tests in which prismatic samples of HMA were subjected to cyclic bending loads under strain controlled tests. Asphalt mixtures with dense, open and gap gradation using conventional and rubber modified binders were tested. The results of all the tests showed the existence of unique curves independent of loading mode, amplitude or frequency within the studied range. This property may be implemented in numerical codes to simulate the behavior of flexible pavements under a variety of field conditions, using a well formulated mechanistic approach.

Validation of a simplified method in viscoelastic continuum damage (VECD) model developed for flexural mode of loading

“…However, Daniel showed that damage can only accumulate during the tensile portion of the each cycle [4]. This assumption is also corroborated by the works of Underwood et al and Mello et al [6,24]. According to this assumption, in this study, only the tensile half of each cycle is used to determine pseudostrain.…”

“…Since distribution of stress and strain within the prismatic specimen under flexural mode of loading is not uniform [24], for simplicity, only stress and strain value in the upper or lower portion of the bending beam's cross-section were used to develop continuum damage model. The on-specimen displacement measurement at the middle of the beam was utilized to calculate the maximum strain and stress at each loading cycle using Eqs.…”

Rubberised stone mastic asphalt mixtures: a performance-related evaluation

“…However, an interaction between rubber particles and bitumen does exist [18] as well as a significant amount of rubber particles being dissolved into the bitumen by means of devulcanisation and depolymerisation [4,33]. It should also be noted that although the fatigue resistance and durability are improved by using higher binder content [34], using excessive binder content could lead to binder drain down and also impair the rutting resistance of the asphalt mixture [12,35].…”

Quantifying Traffic- and Temperature-Induced Fatigue Damages of Asphalt Pavement

“…However, fatigue failure of HMA is the most critical design criteria in flexible pavement and horizontal strain at the bottom of HMA under vehicle load is the key parameter to address this fatigue failure of flexible pavement [8,9]. Moreover, not only does vehicle load produce horizontal strain at the bottom of HMA, but also temperature variations at the bottom of HMA cause a horizontal strain.…”