Effect of Fineness Modulus and Uniformity Coefficient on the Complex Modulus Function of Asphalt Concrete

2017 ◽  
Author(s):  
A. S. M. Asifur Rahman ◽  
Rafiqul A. Tarefder
Keyword(s):  
Asphalt Concrete ◽  
Complex Modulus ◽  
Superposition Principle ◽  
Asphalt Binders ◽  
Modulus Function ◽  
Aggregate Gradation ◽  
Factors Affecting ◽  
Uniformity Coefficient ◽  
Time Temperature Superposition Principle ◽  
Fineness Modulus

Different material attributes such as mix volumetrics, aggregate gradations, and binder characteristics are the factors affecting viscoelastic material functions of asphalt concrete. In this study, the effects of aggregate gradation on the complex modulus function of asphalt concrete are determined. The two distinct properties of the aggregate blend considered in this study are the fineness modulus and the uniformity coefficient. A total of 54, plant produced, asphalt concrete mixtures with asphalt binders having various performance grades and sources were collected from the manufacturing plants. The asphalt-aggregate mixtures were then compacted, cored, and sawed to cylindrical specimens. Three cylindrical specimens from each of the asphalt-aggregate mixtures were prepared and tested in the laboratory for complex or dynamic modulus. After that, average mastercurves of complex modulus and phase angle were generated by applying time-temperature superposition principle. Study showed that the complex modulus function of asphalt concrete is significantly related to the fineness modulus and uniformity coefficient of the aggregate blends used in the asphalt-aggregate mixture.

Dynamic Viscoelastic Properties of SBS Modified Asphalt Based on DSR Testing

2012 ◽  
Vol 598 ◽  
pp. 473-476 ◽  
Author(s):  
Yong Mei Guo ◽  
Wei Chen
Keyword(s):  
Complex Modulus ◽  
Superposition Principle ◽  
Asphalt Binder ◽  
Asphalt Binders ◽  
Frequency Range ◽  
Master Curves ◽  
Temperature Property ◽  
Low Frequencies ◽  
High Temperature Property ◽  
Frequency Sweeps

Five SBS modified asphalts and one base asphalt were selected to carry out frequency sweeps over a wider frequency range using the dynamic shear rheometer (DSR). Six asphalt binders were subjected to sinusoidal loading at 30°C-90°C within the linear viscoelastic limits, and master curves of complex modulus (G*) and phase angle (δ) could be constructed by means of the time-temperature superposition principle (TTSP). The results show that the G* values of SBS modified asphalts are significantly greater than those of base asphalt at low frequencies, but are slightly smaller at high frequencies. Compared with the base asphalt, SBS modified asphalts have narrower master curves of complex modulus, and their phase angles are much smaller within the whole frequency range. This indicates that various properties of SBS modified asphalts, such as high-temperature property, low-temperature property, temperature susceptibility and elastic recoverability, are superior to those of the base asphalt. The G* values of the rolling thin-film oven (RTFO) aged asphalt are larger than those of the unaged asphalt in the whole range of frequencies, demonstrating that the anti-rutting performance of asphalt binder is improved after short-term aging.

Creep Compliance of Polymer-Modified Asphalt, Asphalt Mastic, and Hot-Mix Asphalt

2003 ◽  
Vol 1829 (1) ◽  
pp. 33-38 ◽  
Author(s):  
Ota Vacin ◽  
Jiri Stastna ◽  
Ludo Zanzotto
Keyword(s):  
Creep Compliance ◽  
Superposition Principle ◽  
Asphalt Binder ◽  
Tensile Creep ◽  
Asphalt Binders ◽  
Simple Relationship ◽  
Modified Asphalt ◽  
Asphalt Mastic ◽  
Polymer Modified Asphalt ◽  
Time Temperature Superposition Principle

The possibility of using commercial rheometers for comprehensive testing of asphalt binders, asphalt mastics, and hot-mix asphalts (HMA) is explored. Samples of one polymer-modified asphalt, its mix with fine mineral filler (mastic), and one HMA prepared with the same modified asphalt as binders were tested in the dynamic shear rheometer (DSR) and the bending beam rheometer (BBR). All tested materials can be characterized by their discrete relaxation and retardation spectra (under the condition of small deformations). DSR testing was performed in the plate–plate and the torsion bar geometry. From the obtained relaxation and retardation spectra, the shear compliance, J(t), was calculated and compared with the tensile creep compliance, D(t), measured in BBR (both creep and recovery experiments were run). A simple relationship between J(t) and D(t) was found for the asphalt binder and the asphalt mastic. In the case of HMA, the bulk compliance, B(t), contributes to D(t) at short and long times. Both the Boltzmann superposition principle and the time–temperature superposition principle hold very well for all tested materials at low temperatures. There are qualitative differences, in the rheological behavior, of the asphalt binder and asphalt mastic on one side and the HMA on the other. These differences can be seen in dynamic (DSR) as well as in transient (BBR) experiments.

Effect of Progressive Aging on the Viscoelastic Material Functions of Asphalt Concrete and its Binder

2017 ◽  
Author(s):  
A. S. M. Asifur Rahman ◽  
Hasan M. Faisal ◽  
Rafiqul A. Tarefder
Keyword(s):  
Shear Modulus ◽  
Viscoelastic Material ◽  
Asphalt Concrete ◽  
Complex Modulus ◽  
Superposition Principle ◽  
Asphalt Binder ◽  
Relaxation Modulus ◽  
Concrete Specimen ◽  
Material Functions ◽  
Four Levels

In this study, field collected loose asphalt-aggregate mixtures were used to prepare cylindrical asphalt concrete specimen using a Superpave gyratory compactor and samples were subjected to four levels of aging. Unaged and aged samples were then tested for complex modulus, relaxation modulus, and creep compliance in the laboratory at different temperatures and loading conditions. To determine broadband characteristics, mastercurves of related viscoelastic material functions were determined by applying time-temperature superposition principle. A comparison study showed that increasing levels of aging have significant effect on viscoelastic functions of asphalt concrete. In addition, liquid asphalt binder corresponding to the asphalt-aggregate mixture was tested for complex shear modulus at various levels of aged conditions, using a dynamic shear rheometer. Results showed that even though the binder shear modulus increases significantly with aging, asphalt concrete modulus does not necessarily show similar increment.

scholarly journals COMPARISON OF TWO ASPHALT MIXTURES USING COMPLEX MODULUS TEST IN LIBYAN WEATHER

2019 ◽  
Vol 10 (1) ◽  
pp. 82-92
Author(s):  
Khlifa Saad El atrash ◽  
Gabriel J. Assaf
Keyword(s):  
Laboratory Experiments ◽  
Complex Modulus ◽  
Asphalt Mixtures ◽  
Traffic Load ◽  
Asphalt Binders ◽  
Loading Frequency ◽  
Content Increase ◽  
Aggregate Gradation ◽  
Load Effects ◽  
Phase Angles

The complex modulus test is dependent on temperature and loading frequency. Thus, the results produced from this test will give a more accurate representation of traffic load effects on asphalt pavement. Laboratory experiments were conducted on two different asphalt mixtures for road research projects (Libya/Roads). All specimens had the same mixtures of aggregate gradation GB-20 incorporated with two different asphalt binders PG70-10 and B (60/70). To obtain the master curve, there were some errors at low temperatures (-25, -10 ºC) and high temperature (54 ºC), so these values were discarded. In addition, 2-complex modulus (CM) and phase angles (Phi) in the test were measured at temperatures of -25, -10, -5, 10, 25, 35, and 54ºC, as well as frequencies of 25, 10, 5, 1, 0.5 and 0.1 Hz. The results displayed the influence of the type of binder on the rheology of the mixtures and gradation on the intensity. Hence, using binder PG 70-10 in Libyan asphalt roads may reduce the binder content, increase the mixture workability, and decrease the thermal cracking. The intrinsic characteristics related to binder properties and weather temperature exhibited the most significant impact on the predicted dynamic modulus. Keywords: complex modulus, frequencies, temperatures, sinusoidal, phase angles

Development of a New Dynamic Modulus Predictive Model Based on Binder Viscosity for the Superpave Mixtures of New Mexico

2016 ◽  
Author(s):  
A. S. M. Asifur Rahman ◽  
Rafiqul A. Tarefder
Keyword(s):  
New Mexico ◽  
Predictive Model ◽  
Asphalt Concrete ◽  
Dynamic Modulus ◽  
Design Method ◽  
Superposition Principle ◽  
Asphalt Binder ◽  
Accurate Estimation ◽  
Sigmoid Function ◽  
Uniformity Coefficient

The newly developed mechanistic-empirical pavement design method uses the dynamic modulus as one of the crucial input parameters for the asphalt pavement to be designed or analyzed. This study proposes a new regression-based predictive model to estimate dynamic modulus of asphalt concrete from the viscosity of the asphalt binder used in the asphalt-aggregate mixture. Other parameters related to the aggregate gradation, such as, fineness modulus, and uniformity coefficient and the parameters related to the mixture volumetric are also incorporated in this model. A total of 21 asphalt concrete mixtures with asphalt binders having different performance grades and Superpave gradations were collected from different mixing plants and paving sites at various regions of New Mexico. The collected mixtures were then compacted, cored and sawed to cylindrical specimens. The asphalt concrete specimens were then tested for dynamic modulus at different temperatures and loading frequencies. The time-temperature superposition principle was then applied to develop dynamic modulus mastercurves at 70 °F (21.1 °C) reference temperature. The mastercurves were then fitted by the sigmoid function. The parameters of the sigmoid function were then correlated to the physical attributes of the asphalt concrete samples. Finally, a predictive model is developed to estimate the dynamic modulus of the AC mixtures typically used in New Mexico. Statistical evaluation showed that a fairly accurate estimation of dynamic modulus can be found by using this new dynamic modulus predictive model.

Interconversion of Frequency Domain Complex Modulus to Time Domain Modulus and Compliance of Asphalt Concrete: Numerical Modeling and Laboratory Validation

2016 ◽  
Author(s):  
A. S. M. Asifur Rahman ◽  
Rafiqul A. Tarefder
Keyword(s):  
Viscoelastic Material ◽  
Asphalt Concrete ◽  
Creep Compliance ◽  
Complex Modulus ◽  
Relaxation Modulus ◽  
Modulus Function ◽  
Approximate Methods ◽  
Material Functions ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic

Viscoelastic material functions such as time domain functions, such as, relaxation modulus and creep compliance, or frequency domain function, such as, complex modulus can be used to characterize the linear viscoelastic behavior of asphalt concrete in modeling and analysis of pavement structure. Among these, the complex modulus has been adopted in the recent pavement Mechanistic-Empirical (M-E) design software AASHTOWare-ME. However, for advanced analysis of pavement, such as, use of finite element method requires that the complex modulus function to be converted into relaxation modulus or creep compliance functions. There are a number of exact or approximate methods available in the literature to convert complex modulus function to relaxation modulus or creep compliance functions. All these methods (i.e. exact or approximate methods) are applicable for any linear viscoelastic material up to a certain level of accuracy. However, the applicability and accuracy of these interconversion methods for asphalt concrete material were not studied very much in the past and thus question arises if these methods are even applicable in case of asphalt concrete, and if so, what is the precision level of the interconversion method being used. Therefore, to investigate these facts, this study undertaken an effort to validate a numerical interconversion technique by conducting representative laboratory tests. Cylindrical specimens of asphalt concrete were prepared in the laboratory for conducting complex modulus, relaxation modulus, and creep compliance tests at different test temperatures and loading rates. The time-temperature superposition principle was applied to develop broadband linear viscoelastic material functions. A numerical interconversion technique was used to convert complex modulus function to relaxation modulus and creep compliance functions, and hence, the converted relaxation modulus and creep compliance are compared to the laboratory tested relaxation modulus and creep compliance functions. The comparison showed good agreement with the laboratory test data. Toward the end, a statistical evaluation was conducted to determine if the interconverted material functions are similar to the laboratory tested material functions.

Integration of Atomistic Simulation with Experiment Using Time−Temperature Superposition for a Cross-Linked Epoxy Network

2019 ◽  
Author(s):  
Ketan Khare ◽  
Frederick R. Phelan Jr.
Keyword(s):  
Master Curve ◽  
Glassy State ◽  
Superposition Principle ◽  
Quantitative Comparison ◽  
Time Shift ◽  
Data Sets ◽  
Epoxy Network ◽  
Temperature Superposition ◽  
Time Temperature Superposition ◽  
Time Temperature Superposition Principle

<a></a><a>Quantitative comparison of atomistic simulations with experiment for glass-forming materials is made difficult by the vast mismatch between computationally and experimentally accessible timescales. Recently, we presented results for an epoxy network showing that the computation of specific volume vs. temperature as a function of cooling rate in conjunction with the time–temperature superposition principle (TTSP) enables direct quantitative comparison of simulation with experiment. Here, we follow-up and present results for the translational dynamics of the same material over a temperature range from the rubbery to the glassy state. Using TTSP, we obtain results for translational dynamics out to 10<sup>9</sup> s in TTSP reduced time – a macroscopic timescale. Further, we show that the mean squared displacement (MSD) trends of the network atoms can be collapsed onto a master curve at a reference temperature. The computational master curve is compared with the experimental master curve of the creep compliance for the same network using literature data. We find that the temporal features of the two data sets can be quantitatively compared providing an integrated view relating molecular level dynamics to the macroscopic thermophysical measurement. The time-shift factors needed for the superposition also show excellent agreement with experiment further establishing the veracity of the approach</a>.

Sign in / Sign up

Export Citation Format

Share Document