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.

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.

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.

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.

New Mechanistic Procedure to Predict the Critical Cracking Temperature of Asphalt Concrete from Bending Beam Rheometer and Indirect Tension Test Data

2021 ◽  
pp. 036119812110237
Author(s):  
Md Amanul Hasan ◽  
Rafiqul A. Tarefder
Keyword(s):  
Thermal Stress ◽  
Strain Rate ◽  
Asphalt Concrete ◽  
Superposition Principle ◽  
Relaxation Modulus ◽  
Model Parameters ◽  
Creep Data ◽  
Bending Beam Rheometer ◽  
Indirect Tension ◽  
Critical Cracking Temperature

This study presents a new mechanistic procedure for determining the critical cracking temperature of asphalt concrete (AC) using data from bending beam rheometer (BBR) test of asphalt binder and indirect tension (IDT) test of AC. This new procedure uses BBR creep data to generate the mixture relaxation modulus mastercurve by utilizing the Hirsch model, time-temperature superposition principle, and Prony series-based interconversion method. The Hirsch model parameters are calibrated by comparing creep data from BBR and IDT creep tests performed at the same temperature. Boltzmann hereditary integral and second-order heat equation are then used to calculate thermal stress from the developed relaxation modulus mastercurve. IDT strength data is transferred from test strain rate to thermal strain rate using the viscoelastic continuum damage model. Since a strain gauge is not attached for traditional laboratory IDT strength testing, this study derived an analytical equation based on the Hondros solution to compute the horizontal strain rate from the applied vertical displacement rate. Finally, the critical cracking temperature is determined by coupling the thermal stress and strength profiles. Using the procedure presented in this paper, the critical cracking temperatures of four AC mixtures were predicted from BBR and IDT data. Their actual critical cracking temperatures were measured using thermal stress restrained specimen test performed in the laboratory to validate the method. The predicted critical cracking temperatures are found to be very close to the laboratory measured values. The developed procedure has substantial practical and technical importance in predicting the critical cracking temperature of AC because it utilizes widely available BBR and IDT tests.

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.

Relationships Among Rate-Dependent Stiffnesses of Asphalt Concrete Using Laboratory and Field Test Methods

1998 ◽  
Vol 1630 (1) ◽  
pp. 3-9 ◽  
Author(s):  
Jo Sias Daniel ◽  
Y. Richard Kim
Keyword(s):  
Asphalt Concrete ◽  
Creep Compliance ◽  
Complex Modulus ◽  
Relaxation Modulus ◽  
Test Methods ◽  
Rate Dependent ◽  
Creep Stiffness ◽  
Linear Viscoelastic ◽  
Linear Viscoelastic Theory ◽  
Falling Weight

As the application of nondestructive testing on pavements in service becomes more frequent, it is increasingly important to relate the resulting stiffnesses to those from laboratory test methods. The relationship among stiffnesses measured from five test methods currently used for asphalt concrete is addressed: creep compliance, complex modulus, impact resonance, falling weight deflectometer, and surface wave. Established relationships from linear viscoelastic theory are used to relate stiffnesses, including a comparison of creep stiffness, S( t), and relaxation modulus, E( t), calculated from creep compliance, D( t). Using laboratory and field measured stiffnesses, a linear relationship was discovered between stiffness and frequency on a log-log scale.

scholarly journals Displacement Investigation of KNN-Bitumen-Based Piezoceramics in Asphalt Concrete

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Ning Tang ◽  
Kaikai Yang ◽  
Wenhao Pan ◽  
Limei Wu ◽  
Qing Wang ◽  
...  
Keyword(s):  
Asphalt Concrete ◽  
Electromechanical Coupling ◽  
Asphalt Binder ◽  
Test System ◽  
Displacement Sensor ◽  
Research Focus ◽  
Vehicle Load ◽  
Piezoceramic Element ◽  
Piezoelectric Field ◽  
Natural Situation

Piezoelectric material has excellent characteristics of electromechanical coupling so that it could be widely applied in structural health monitoring field. Nondestructive testing of piezoelectric technique becomes a research focus on piezoelectric field. Asphalt concrete produces cumulative damage under the multiple repeated vehicle load and natural situation, so it is suited material and structure for nondestructive application. In this study, a test system was established by driving power of piezoceramic, laser displacement sensor, computer, and piezo-embedded asphalt concrete. Displacement, hysteresis, creeps, and dynamic behavior of KNN piezoceramic element embedded in asphalt concrete were tested. The results indicate that displacement output attained 0.4 μm to 0.7 μm when the loads were from 0 N to 150 N. The hysteresis was not obvious when the load was from 0 N to 100 N, aside from higher loads. The creep phenomenon can be divided into two parts: uptrend and balance. The more serious the asphalt binder ageing is, the larger the displacement is, when piezo-asphalt concrete has already been in serious ageing.

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