Multiscale testing-analysis of asphaltic materials considering viscoelastic and viscoplastic deformation (original) (raw)
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Modeling the Impact of Testing Mode on the Viscoelastic Behavior of Asphalt Concrete
2023
The variations in the viscoelastic characteristics of asphalt concrete due to testing mode are assessed and modeled in the present investigation. Asphalt concrete mixture was prepared at its optimum asphalt binder requirement and compacted in slab mold with the aid of roller compaction. Beam specimens of 6.2 cm width, 5.6 cm depth, and 40 cm length, were obtained from the slab samples with the aid of a diamond saw, and tested using controlled stress and strain techniques under dynamic flexural stresses. The viscoelastic properties such as the phase angle, cumulative dissipated energy, permanent deformation, flexural stiffness, and micro strain were monitored and modeled among the two testing techniques. It was noticed that higher micro strain and permanent deformation are detected when testing the asphalt concrete specimens under constant strain mode. However, higher phase angle, flexural stiffness, and energy dissipation could be observed under the constant stress mode of the test.
Determination of Asphalt Concrete Viscosity by the Four-Point Bending Test
International Journal of Research -GRANTHAALAYAH, 2019
In this work, a model for the dynamical four-point bending test is present, with particular emphasis on application to an asphalt concrete (AC) composite, a viscoelastic material, based on the Euler-Bernoulli theory, which approaches an equation where the Young modulus E can be substituted by the operator (E + γ∂/∂t), where γ is an internal damping parameter associated to the binder viscoelasticity and t is the time. As course aggregate in the composition of the AC mixture, the sintered aggregate of calcined clay was used, interesting to be employed as an alternative to the lack of natural course aggregate in some regions of the planet, where the presence of sedimentary rocks prevails. The results indicated that γ decreases with the temperature and loading frequency and the apparent noise in the stiffness versus strain curve is resulted from the natural vibration mode of the beam.
Viscoplasticity Modeling of Asphalt Concrete Behavior
Recent Advances in Materials Characterization and Modeling of Pavement Systems, 2003
A constitutive model based on an extended form of the Schapery continuum damage formulation (Ha and Schapery, 1998; Schapery, 1999) is currently being evaluated and developed as a comprehensive material model for asphalt concrete. This model considers the viscoelastic, damage, and viscoplastic components of asphalt concrete behavior over the full range conditions of interest for the mechanistic prediction of flexible pavement distresses. The focus of the present paper is limited to the viscoplastic response component at intermediate and high temperatures. The results confirm earlier findings (Schwartz et al., 2002) that asphalt concrete in compression is a thermorheologically simple material well into the large strain viscoplastic regime at elevated temperature. The study demonstrates that the proposed viscoplastic model component provides a good representation of the viscoplastic response of asphalt concrete in uniaxial unconfined compression. Given the validity of time-temperature superposition for viscoplastic response, the viscoplastic material parameters can be calibrated from a limited number of uniform time and uniform load creep and recovery tests. Typical viscoplastic material parameters are derived for a representative asphalt concrete mixture.
Micromechanical Analysis of Viscoelastic Properties of Asphalt Concretes
Transportation Research Record, 2002
This paper describes a methodology for relating the microstructure of asphalt concretes to their viscoelastic behavior. Imaging techniques are used for capturing the asphalt concrete microstructure and the finite element method (FEM) is used for modeling its stress-strain behavior in the time domain. Aggregates are modeled as linear elastic, while the binder is modeled through mechanistic models as either linear viscoelastic or non-linear viscoelastic. The binder viscoelastic properties are input into the FEM algorithm using two methods, a built-in viscoelastic function and a userspecified material characterization subroutine. The latter handles non-linearity in an iterative piece-wise linear fashion, whereby the mechanistic binder model parameters are updated as a function of the strain level. For each strain level, mechanistic models are fitted to describe binder viscoelastic behavior based on Dynamic Shear Rheometer data.
International Journal of Advances in Engineering Sciences and Applied Mathematics, 2011
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The aim of this study is to assess the viscoelastic parameters (i.e., phase angle and dynamic modulus) of asphalt concrete-wearing course (AC-WC) and hot rolled sheet-wearing course (HRS-WC) mixtures obtained from the dynamic modulus test. This study was accomplished in four stages: determining optimum asphalt content using Marshall mix design procedure, stability and flow parameters from Marshall test, viscoelastic parameters from dynamic modulus testing and finally the generation of dynamic modulus master curves at a reference temperature of 25 • C. The results showed that at the same temperature, the dynamic modulus of AC-WC and HRS-WC mixtures tended to increase with escalating the loading frequency, while dynamic modulus decreases with an increase in the test temperature at constant loading frequency. Furthermore, the dynamic modulus of the AC-WC mixture was recorded as 100% higher than the HRS-WC asphalt mixture. The phase angle, however, showed contradictory behavior with that shown in dynamic modulus. The phase angle of the AC-WC mixture and HRS-WC asphalt mixture showed almost the same behavior. Similarly, the dynamic modulus master curves of AC-WC and HRS-WC asphalt mixtures can be used to predict the dynamic modulus at the frequency range of 0.01 to 10 Hz and a reference temperature of 25 • C. The results were also used to evaluate the rutting and fatigue performance of AC-WC and HRS-WC.
Arabian Journal for Science and Engineering, 2017
At present, Italian technical specifications only provide stiffness measurements in few cases, whereas they require the execution of the static indirect tensile strength test, both in mix design and in quality control phases. Despite this test is typically carried out only to determine the material strength, it is, however, possible to obtain a measure of the specimen stiffness properties from the stress-strain curve. The present paper deals with the correlation between asphalt concrete stiffness measurements obtained through dynamic indirect tensile tests, according to EN 12697-26, and static indirect tensile strength tests, according to EN 12697-23. In particular, data from static tests have been processed to obtain stiffness measurements through the application of Hondros' theory or graphically from the stress-strain curve. Although based on empirical derivation, this relationship would enable the laboratories that are not equipped with a proper machine for dynamic modulus tests to estimate the stiffness properties of the bituminous material, by exclusively performing simple static tests. The experimental program included static and dynamic indirect tensile tests at 10, 20 and 30 • C on three asphalt concretes, different for binder type and compacted to two air voids contents. Results proved that good correlations (R 2 values higher than 0.92) can be established between dynamic modulus and static moduli, independently from test conditions and mixture composition.
2010
The results are presented of a laboratory study on the Stiffness and the Resilient Modulus of bituminous mixes determined by the Indirect Tensile Test, conducted according to the EN 12697-26, Annex C and the ASTM D 4123 standards. The testing was performed on high-performance bituminous mixtures, including polymer modified base-binder and wearing course asphalt concretes, stone mastic asphalt and porous asphalt. The course aggregate grading of all the mixtures contains Electric Arc Furnace (EAF) steel slags, up to a maximum content of 45%. The purpose was first of all to analyze quantitatively the controlled strain and the controlled stress loading procedure, that characterize the EN and the ASTM standards respectively, at various temperatures, strain levels, repetition periods and rise times. A second aim was to check the applicability of the above-mentioned regulations to both dense, as well as porous asphalt mixtures. The results of this study demonstrate that the standard contro...
Mechanics of Time-Dependent Materials, 2011
This paper presents a simple and practical approach to obtain the continuous relaxation and retardation spectra of asphalt concrete directly from the complex (dynamic) modulus test data. The spectra thus obtained are continuous functions of relaxation and retardation time. The major advantage of this method is that the continuous form is directly obtained from the master curves which are readily available from the standard characterization tests of linearly viscoelastic behavior of asphalt concrete. The continuous spectrum method offers efficient alternative to the numerical computation of discrete spectra and can be easily used for modeling viscoelastic behavior. In this research, asphalt concrete specimens have been tested for linearly viscoelastic characterization. The linearly viscoelastic test data have been used to develop storage modulus and storage compliance master curves. The continuous spectra are obtained from the fitted sigmoid function of the master curves via the inverse integral transform. The continuous spectra are shown to be the limiting case of the discrete distributions. The continuous spectra and the time-domain viscoelastic functions (relaxation modulus and creep compliance) computed from the spectra matched very well with the approximate solutions. It is observed that the shape of the spectra is dependent on the master curve parameters. The continuous spectra thus obtained can easily be implemented in material mix design process. Prony-series coefficients can be easily obtained from the continuous spectra and used in numerical analysis such as finite element analysis.