Fatigue damage analysis in asphalt concrete mixtures using the dissipated energy approach

Abstract

An asphalt concrete damage-energy fatigue approach based on the concept of change in dissipated energy is presented in this paper. The damage-energy based fatigue approach is simple and based on a sound theoretical background. The central concept of the energy approach is the energy fatigue curve, which is based on two key elements, namely the plateau value (PV) and the number of load cycles to true failure (N tf ). The plateau value represents the constant value of the percentage of dissipated energy that produces damage to the material under cyclic loading. Failure is defined as the number of load cycles at which this percentage of dissipated energy begins to increase rapidly, indicating instability. Flexural fatigue testing was used to test hundreds of asphalt concrete beams, mainly under controlledstrain testing conditions. It was found that PV is highly dependent on the initial loading conditions, stress, strain, and dissipated energy. As a result, it can be used conveniently in pavement design. The number of load cycles to 50% reduction in initial stiffness was found to be highly correlated with the new failure point (N tf ). Using the dissipated energy concepts in fatigue analysis makes it possible to account for damage accumulation in a straightforward manner.Key words: fatigue of asphalt concrete, dissipated energy, damage, energy ratio. Résumé :Cet article présente un rapprochement de détermination de la fatigue par dommage-énergie du béton bitumineux basée sur le changement dans le concept de l'énergie dissipée. Ce rapprochement de détermination de la fatigue basée sur le dommage-énergie est simple et basée sur une théorie saine. Le concept principal de l'approche énergé-tique est la courbe fatigue énergie. Cette courbe fatigue énergie est fondée sur deux éléments clés : la valeur plateau (PV) et le nombre de cycles de chargement jusqu'à la défaillance réelle (N tf ). La valeur plateau représente la valeur constante du pourcentage d'énergie dissipée qui produit des dommages au matériel sous chargement cyclique. La dé-faillance est définie par le nombre de cycles de chargement auquel ce pourcentage d'énergie dissipée commence à s'accroître rapidement, indiquant ainsi une instabilité. Des essais de fatigue en flexion ont été utilisés pour mettre à l'épreuve des centaines de poutres en béton bitumineux, principalement sous des conditions contrôlées de contrainte. Il a été découvert que la PV dépend grandement des conditions initiales de charge, de la contrainte et de déformation et de l'énergie dissipée. Cela permet de l'utiliser dans la conception des chaussées. Le nombre de cycles de charge pour une réduction de rigidité initiale de 50 % est fortement corrélé au nouveau point de défaillance (N tf ). En utilisant les concepts d'énergie dissipée dans l'analyse de la fatigue, il est possible de tenir compte directement de l'accumulation des dommages.Mots clés : fatigue du béton bitumineux, énergie dissipée, dommage, rapport d'énergie.[Traduit par la Rédaction] Ghuzlan and Carpenter 901

Fatigue characterization of asphalt mixes containing electric arc furnace (EAF) steel slag subjected to long term aging

“…(a) Row method (by plotting the stiffness ratio versus the number of load cycles; where fatigue life is defined as the peak of the curve [20]); (b) Pronk and Hopman method, based on dissipated energy (by plotting energy ratio versus number of load cycles); where fatigue life is defined as the peak of the curve [19]; and, (c) RDEC method: as an energy based approach, RDEC is fundamental and has been demonstrated to be valid for different testing methods such as flexural bending beam fatigue [22,9,10,8], uniaxial tension, and various materials, including both asphalt concrete and Portland Cement Concrete mixes [23]. where RDEC is theratio of dissipated energy change per load cycle; DE n the dissipated energy produced in load cycle n, kPa; and DE n+1 is the dissipated energy produced in load cycle n + 1, kPa.…”

Tire Crumb Rubber Effect on Hot Bituminous Mixtures Fatigue-Cracking Behaviour

“…Nevertheless, any damaged material is also characterized by a corresponding change in dissipated energy (Ghuzlan 2001). Because of this, it is necessary to use the ratio of dissipated energy change (RDEC, Eqn (1)) to analyse the evolution and real quantification of crack damage in the mix (Carpenter, Jansen 1997;Ghuzlan, Carpenter 2000;Shen, Carpenter 2007).…”

Three‐dimensional analysis of fatigue tests on bituminous mixtures

“…[2][3][4][5][6][7][8][9][10][11][12][13] It has been shown that three phases can be observed during fatigue test on bituminous mixtures. Two types of controlled loading are generally applied for fatigue characterization: constant stress amplitude and constant strain amplitude.…”

“…Different approaches and different types of tests have been developed to characterize fatigue and fatigue damage law. [2][3][4][5][6][7][8][9][10][11][12][13] It has been shown that three phases can be observed during fatigue test on bituminous mixtures. 5,[14][15][16][17] The first phase corresponds to an adaptation phase.…”