Viscoelastic Analysis of Asphalt Mastic Based on Micromechanics

2011 ◽  
Vol 266 ◽  
pp. 38-41
Author(s):  
Jiu Peng Zhang ◽  
Li Xu ◽  
Jian Zhong Pei
Keyword(s):  
Shear Modulus ◽  
Chemical Interaction ◽  
Hydrated Lime ◽  
Asphalt Binders ◽  
Dynamic Shear Modulus ◽  
Dynamic Shear ◽  
Complex Shear Modulus ◽  
Asphalt Mastic ◽  
Physico Chemical ◽  
Complex Shear

In this study, the stiffening effect of fillers on asphalt binders was characterized through micromechanics and rheology methods. The dynamic shear rheometer (DSR) was used to measure viscoelastic properties of asphalt mastic. Mechanical volume filling effects and additional interacting mechanisms within mastic systems are discussed on the basis of micromechanics-rheology model to predict the complex shear modulus of asphalt mastic from the measured mastic data. It is observed that the phase angle ranges from 88.8o to 89.0o, does not significantly change due to limestone fillers addition. The analytical model prediction of complex shear modulus based on the dynamic shear modulus can be used. Using the nonlinear regression, the Einstein coefficient KE is 4.22, 5.09 and 7.44 for asphalt mixed with limestone, cement and hydrated lime, respectively. Beside, the SEM results explain why the mastic system with hydrated lime shows the highest KE. The behavior of hydrated lime fillers filled mastics is probably due to physico–chemical interaction, which can be validated by further research.

Research on Interaction between Asphalt and Filler Based on DSR Test

2013 ◽  
Vol 723 ◽  
pp. 480-487 ◽  
Author(s):  
Jiu Peng Zhang ◽  
Jian Zhong Pei ◽  
Yan Wei Li
Keyword(s):  
Shear Modulus ◽  
Volume Fraction ◽  
Hydrated Lime ◽  
Interaction Coefficient ◽  
Complex Shear Modulus ◽  
Volume Fractions ◽  
Asphalt Mastic ◽  
Complex Shear ◽  
Asphalt Mastics ◽  
Einstein Coefficient

To explain the interactive effect between asphalt and fillers in the asphalt mastic, it is probably to start with an assessment of the rheology properties, since asphalt mastics are viscoelastic materials. In this study, firstly prepare the asphalt mastics with different dosage of limestone filler, and the volume fractions of fillers were 0, 14, 24, 32, 39 and 45%. And then, the same asphalt is mixed with different fillers, such as cement and hydrated lime, and the volume fractions of fillers were 18, 23, 28and 33%. DSR test was conducted on all of the asphalt mastic specimens to measure the complex shear modulus G* at different temperature. The volume filling effects and interaction between asphalt and filler are discussed on the analysis of complex shear modulus coefficient and Nielsens model model. It is obviously that G* of asphalt mastics decrease with the test temperature, but increase with the volume fraction of filler. A function relation between complex shear modulus coefficient and volume fraction of fillers is established, and the interaction coefficient α is proposed. For limestone, cement and hydrated lime filler, the interaction coefficient α values are 0.301, 0.317 and 0.429 respectively. Based on Nielsens model and DSR test data, the Einstein coefficient KE is calculated, and Einstein coefficients are 3.761, 5.09 and 7.44 for asphalt-limestone mastic, asphalt-cement mastic and asphalt-hydrated lime mastic respectively. Both the interaction coefficient α and Einstein coefficient KE can be used to represent the interaction between asphalt binder and filler. The bigger value means the better interaction.

Validation of Magnetic Resonance Elastography by Dynamic Shear Testing in the Shear Wave Regime

2010 ◽  
Author(s):  
Ruth J. Okamoto ◽  
Erik H. Clayton ◽  
Kate S. Wilson ◽  
Philip V. Bayly
Keyword(s):  
Magnetic Resonance ◽  
Shear Modulus ◽  
Shear Wave ◽  
Shear Force ◽  
Magnetic Resonance Elastography ◽  
Dynamic Shear ◽  
Complex Shear Modulus ◽  
Shear Testing ◽  
Complex Shear ◽  
Propagating Shear

Magnetic resonance elastography (MRE) is a novel experimental technique for probing the dynamic shear modulus of soft biological tissue non-invasively and in vivo. MRE utilizes a standard MRI scanner to acquire images of propagating shear waves through a specimen that is subject to external harmonic mechanical actuation; commonly at frequencies in excess of 200Hz. At steady state, the wavelength of the propagating shear wave can be used to estimate the shear modulus of the tissue. Dynamic shear testing (DST) is also used to characterize soft biomaterials. Thin samples of the material are subject to oscillatory shear strains. Shear force is measured, and converted to shear stress — analysis of this data of a range of frequencies gives a complex shear modulus. The data analysis method assumes that the shear displacement is linear and shear strain is constant through the thickness of the sample. In soft tissues, very thin samples are typically used to avoid inertial effects at higher frequencies. As the thickness of the sample decreases, it is more difficult to cut samples of uniform thickness and to maintain structural integrity of the sample. Thus in practice, measurements of brain tissue properties using DST without inertial correction are limited to low frequencies. In this work, we bridge the frequency regimes of DST and MRE by testing thick samples using DST over a range of frequencies that generates a shear wave in the sample, with a corresponding peak in the measured shear force. The frequency and magnitude of this peak give additional information about the complex shear modulus of the material being tested, and these DST results are interpreted using a finite element (FE) model of the sample. Using this method, we can obtain an estimate of shear modulus in an intermediate frequency regime between that of standard DST and MRE.

scholarly journals Micromechanical Prediction Model of Viscoelastic Properties for Asphalt Mastic Based on Morphologically Representative Pattern Approach

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Zhichen Wang ◽  
Naisheng Guo ◽  
Xu Yang ◽  
Shuang Wang
Keyword(s):  
Shear Modulus ◽  
Prediction Model ◽  
Viscoelastic Properties ◽  
Volume Fraction ◽  
Complex Modulus ◽  
Homogenization Theory ◽  
Dynamic Shear Modulus ◽  
Dynamic Shear ◽  
Low Frequencies ◽  
Asphalt Mastic

This paper is devoted to the introduction of physicochemical, filler size, and distribution effect in micromechanical predictions of the overall viscoelastic properties of asphalt mastic. In order to account for the three effects, the morphologically representative pattern (MRP) approach was employed. The MRP model was improved due to the arduous practical use of equivalent modulus formula solution. Then, a homogeneous morphologically representative model (H-MRP) with the explicit solution was established based on the homogenization theory. Asphalt mastic is regarded as a composite material consisting of filler particles coated structural asphalt and free asphalt considering the physicochemical effect. An additional interphase surrounding particles was introduced in the H-MRP model. Thus, a modified H-MRP model was established. Using the proposed model, a viscoelastic equation was derived to predict the complex modulus and subsequently the dynamic modulus of asphalt mastic based on the elastic-viscoelastic correspondence principle. The dynamic shear rheological tests were conducted to verify the prediction model. The results show that the predicted modulus presents an acceptable precision for asphalt mastic mixed with 10% and 20% fillers volume fraction, as compared to the measured ones. The predicted modulus agrees reasonably well with the measured ones at high frequencies for asphalt mastic mixed with 30% and 40% fillers volume fraction. However, it exhibits underestimated modulus at low frequencies. The reasons for the discrepancy between predicted and measured dynamic shear modulus and the factors affecting the dynamic shear modulus were also explored in the paper.

Micromechanical-Rheology Model for Predicting the Complex Shear Modulus of Asphalt Mastic

2010 ◽  
Vol 168-170 ◽  
pp. 523-527 ◽  
Author(s):  
Jiu Peng Zhang ◽  
Jian Zhong Pei ◽  
Bing Gang Wang
Keyword(s):  
Shear Modulus ◽  
Viscoelastic Properties ◽  
Interactive Effect ◽  
Packing Fraction ◽  
Complex Shear Modulus ◽  
Asphalt Mastic ◽  
Complex Shear ◽  
Asphalt Mastics ◽  
Einstein Coefficient ◽  
Rheology Model

The dynamic shear rheometer (DSR) was used to measure viscoelastic properties of asphalt mastic. Mechanical volume filling effects and additional interacting mechanisms within mastic systems are discussed on the basis of micromechanical-rheology model to predict the complex shear modulus of asphalt mastic from the measured mastic data. The Einstein coefficient is 3.761, and the maximum volumetric packing fraction is 0.562 for the measured asphalt mastic. The predicted G* of asphalt mastics is very close to the actual value, and the relative error is not exceeding 10%. The micromechanical-rheology model can predict the complex shear modulus of the asphalt mastic from the viscoelastic property of neat asphalt, the volumetric filler effect and an interactive effect between the filler and the asphalt.

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