Shift Factors for Asphalt Fatigue from Full-Scale Testing

Transportation Research Record: Journal of the Transportation R

Denneman

et al. 2018

Self Cite

An experimental study was conducted to determine the effect of haversine and sine displacement waveforms on four-point flexural beam fatigue test results for hot mix asphalt. Seven asphalt mixtures with different gradations, binder types, and binder contents were tested for this study. Four of the mixes were tested in California and three in Australia. The mixes were tested at different strain levels under both waveforms in displacement-controlled mode without rest periods. The comparison showed no differences between haversine and sine testing modes for six of the seven mixtures. Fatigue life, the shape of the stiffness reduction curves, initial dynamic moduli and phase angles, and Black diagrams were essentially the same for both testing modes. This similarity was attributed to the viscoelastic nature of the asphalt mix. Because of asphalt’s viscoelasticity, the beam at-rest position in haversine testing will rapidly move to halfway between zero and maximum displacement, and so the same stress is produced by haversine and sine displacement waveforms as soon as the peak-to-peak amplitudes are equal. For one of the seven mixes, sinusoidal testing produced considerably longer fatigue lives, although it is believed this mix is an outlier and can be ignored. Based on these results, it was concluded that there is no compelling reason to recommend sinusoidal over haversine testing mode, or vice versa. A practical reason to recommend the sine testing mode is that the stress in the haversine alternative becomes sinusoidal after a small number of load repetitions.

mentioning

confidence: 88%

Sine versus Haversine Displacement Waveform Comparison for Hot Mix Asphalt Four-Point Bending Fatigue Testing

Transportation Research Record: Journal of the Transportation R

Denneman

et al. 2018

Self Cite

“…Once ω was determined, it was possible to determine the asphalt modulus for any combination of frequency and temperature by using Equation 3, which is part of the CalME asphalt damage models. Details about the application of the CalME model to CEDEX sections are available elsewhere (6,9).…”

Section: Evolution Of Asphalt Damage During the Testmentioning

confidence: 99%

Evaluation of Structural Response of Cracked Pavements at CEDEX Transport Research Center Test Track

Transportation Research Record: Journal of the Transportation R

Ayuso

Jáuregui

2013

Self Cite

The structural response of a flexible pavement typically is modeled with the multilayer linear elastic theory. This theory is applicable to almost all mechanistic–empirical design procedures but is also used in other fields of pavement engineering, such as in the interpretation of deflection data for assessing a pavement's structural condition. The applicability of this theory, even with some limitations, has been validated for new or undamaged pavements when the hypothesis of continuity is realistic. However, for modeling the structural response of damaged pavements, the presence of discrete cracks is not compatible with continuum mechanics theories. Three flexible sections at the CEDEX Transport Research Center test track were instrumented with sensors. The structural response under moving vehicles was systematically measured for different response variables during a full-scale experiment in which 1.3 million loads were applied. The structural response measured at the beginning of the experiment, when asphalt damage was null, was used as a reference for comparison of the evolution of response during the test. The test showed that the evolution of the response variables could be explained by continuum mechanics, in particular by linear elasticity, as soon as asphalt damage was uniformly distributed in the material. When discrete cracking appeared, the response started to deviate from the response predicted by multilayer linear elastic models. Adoption of a rational approach for determination of the modulus of the asphalt layers is shown to be important.

“…The results presented are part of a research effort the outcomes of which have been included in two papers. The first one was focused on damage prediction and in particular on the transition from a fatigue model calibrated in the laboratory to the field (3). The current paper is focused on the evolution of asphalt layer stiffness during a full-scale test as a consequence of the combined effects of damage, aging, and densification under traffic.…”

Section: Objectivementioning

confidence: 99%

Evolution of Asphalt Mixture Stiffness under Combined Effects of Damage, Aging, and Densification under Traffic

Transportation Research Record: Journal of the Transportation R

Ayuso

Jáuregui

2012

Self Cite

The long-term evolution of asphalt mixture stiffness in the field represents a complex process in which three factors play an essential role: damage, aging, and densification under traffic. To take the factors into account adequately, not only must the level of each factor be known, but also how each level modifies the modulus of the asphalt mixture for the temperature and frequency range corresponding to field conditions. The research presented is based on experimental data from four flexible sections tested at the test track of the Centro de Estudios y Experimentación de Obras Públicas (CEDEX), in Spain. The stiffness of the asphalt layer was periodically evaluated with falling weight deflectometer back-calculation and with dynamic modulus testing in the laboratory. During a 28-month period, 1,323,600 loads were applied on the pavements. This loading caused a high level of deterioration in all sections and significant asphalt densification. The loading also provided time for some aging effects to develop. From the results of this full-scale test, different conclusions could be deduced concerning the evolution of damage, aging, and densification and how this evolution modifies the stiffness of the asphalt mixture. The effects of changes in the parameters of the original master curve have also been quantified. The model and methodology incorporated in the CalME design procedure were successfully used to reproduce the evolution of the asphalt layer modulus during the test. In particular, the assumptions of this model regarding how the dynamic modulus master curve was modified by each of the three factors were found to be valid for this experiment.