1887

n Journal of the South African Institution of Civil Engineering = Joernaal van die Suid-Afrikaanse Instituut van Siviele Ingenieurswese - The use of the correspondence principle towards the fatigue characterisation of asphalt concrete : technical paper

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Abstract

Prediction of the performance of asphalt concrete under realistic traffic conditions needs a sound understanding of the hysteretic stress-strain behaviour of asphalt concrete mixtures under repetitive traffic loading. Fatigue cracking caused by repetitive traffic loading is one of the major distresses in asphalt concrete pavement. The most common fatigue model relates the initial strain or stress levels applied during tests to the fatigue life, without taking into account damage evolution. As a result this fatigue model grossly underpredicts field fatigue life and the introduction of laboratory to field shift factors is necessary. The aim of this paper is, therefore, to introduce a methodology capable of predicting the fatigue performance of asphalt concrete considering damage evolution. Other aspects, such as difference in loading, the changing field environmental conditions, as well as different support conditions, which also necessitates the introduction of shift factors, fall outside the scope of the present research. The correspondence principle was used to achieve this objective, owing to its ability to separately evaluate the three major mechanisms that take place in the asphalt concrete when subjected to repetitive loading with various durations of rest periods: fatigue, which can be regarded as damage accumulation due to flow and crack propagation, relaxation of stresses, related to the viscoelastic nature of asphalt concrete, and chemical healing, across microcrack and macrocrack interfaces, during rest periods. Furthermore, the correspondence principle was used to derive a constitutive equation where damage mechanisms were accounted for. Finally, a fatigue prediction curve was derived based on this constitutive modelling approach. As a result, a higher fatigue life, in terms of number of load applications to failure, was obtained by using this methodology, indicating more realistic fatigue life prediction and less necessity for the use of shift factors. This paper is based on the MEng project report submitted to the University of Pretoria by the first author titled 'Fatigue characterization of asphalt concrete using viscoelasticity and damage theory'.

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/content/civileng/44/2/EJC26922
2002-01-01
2016-12-08
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