scholarly journals Experimental Evaluation and Modeling of Physical Hardening in Asphalt Binders

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 19
Author(s):  
Chiara Tozzi ◽  
Davide Dalmazzo ◽  
Orazio Baglieri ◽  
Ezio Santagata
Keyword(s):  
Experimental Evaluation ◽  
Superposition Principle ◽  
Asphalt Binders ◽  
Rheological Parameters ◽  
Creep Tests ◽  
Physical Hardening ◽  
Ranking Criteria ◽  
In Series ◽  
Short And Long Term ◽  
Improved Model

The research described in this paper deals with the experimental evaluation and modeling of physical hardening in asphalt binders. The term physical hardening refers to a reversible phenomenon occurring at low temperatures that causes time-dependent changes in viscoelastic properties. The experimental approach, followed to quantitatively assess physical hardening, was based on flexural creep tests carried out by means of the Bending Beam Rheometer at various temperatures and conditioning times. The results obtained confirmed that hardening phenomena have a significant influence on the creep response of asphalt binders, to an extent that can be quantitatively assessed by referring to the appropriate rheological parameters and by applying the loading time–conditioning time superposition principle. The experimental data were fitted to a mechanical model proposed in the literature (composed of a single Kelvin–Voigt element) and thereafter to an improved model (with two Kelvin–Voigt elements in series). Both models were assessed in terms of their prediction accuracy. The improved model was found to better describe physical hardening effects in the case of both short- and long-term conditioning. Practical implications of the study were finally highlighted by referring to possible ranking criteria to be introduced in acceptance procedures for the comparative evaluation of asphalt binders.

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.

scholarly journals Nonlinear Viscoelastic–Plastic Creep Model Based on Coal Multistage Creep Tests and Experimental Validation

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3468 ◽  
Author(s):  
Junxiang Zhang ◽  
Bo Li ◽  
Conghui Zhang ◽  
Peng Li
Keyword(s):  
Creep Behavior ◽  
Physical Property ◽  
Creep Model ◽  
Creep Process ◽  
Creep Tests ◽  
Model Based ◽  
Nonlinear Viscoelastic ◽  
Improved Model ◽  
And Control ◽  
Plastic Creep

The development of fractures, which determine the complexity of coal creep characteristics, is the main physical property of coal relative to other rocks. This study conducted a series of multistage creep tests to investigate the creep behavior of coal under different stress levels. A negative elastic modulus and a non-Newtonian component were introduced into the classical Nishihara model based on the theoretical analysis of the experimental results to propose a nonlinear viscoelastic–plastic creep model for describing the non-decay creep behavior of coal. The validity of the model was verified by experimental data. The results show that this improved model can preferably exhibit decelerating, steady state, and accelerating creep behavior during the non-decay creep process. The fitting accuracy of the improved model was significantly higher than that of the classical Nishihara model. Given that acceleration creep is a critical stage in predicting the instability and failure of coal, its successful description using this improved model is crucial for the prevention and control of coal dynamic disasters.

Use of Viscosity Standard Fluid To Control Quality of Rheological Measurements for Characterizing Asphalt Binders

1997 ◽  
Vol 1586 (1) ◽  
pp. 24-31
Author(s):  
Raj Dongré ◽  
Satish Ramaiah ◽  
John D’Angelo
Keyword(s):  
Control Charts ◽  
High Viscosity ◽  
Asphalt Binders ◽  
Rheological Parameters ◽  
Reference Laboratory ◽  
Statistical Process ◽  
Standard Material ◽  
Rheological Measurements ◽  
Statistical Process Control Charts ◽  
Repeatability And Reproducibility

The results of a study to establish a protocol for calibrating and maintaining Superpave rheometers are described. The reference standard material used was supplied by Cannon Instrument Co. The material (high viscosity standard) is designated as N2700000 and is supplied with ASTM traceable values of steady shear viscosity at various Superpave specification temperatures. The main objective was to determine whether sound calibration practices and adequate training can improve the repeatability and reproducibility of the rheological parameters required in the Superpave binder specification. Ten laboratories participated in the study. The results indicate that the viscosity standard can be used as a standard fluid to calibrate and maintain the Superpave rheometers. The repeatability and reproducibility data were compared with similar estimates reported by the AASHTO Materials Reference Laboratory. It was found that the reproducibility (between-laboratory variation) improved by a factor of two and repeatability (within-laboratory variation) improved modestly. With these results, a protocol for using the standard was also developed. Further analysis of results is under way to determine the frequency of calibration and maintenance required to obtain consistent rheological measurements. The results of this analysis and efforts to implement statistical process control charts for calibration and maintenance of rheometers using the standard reference fluid (Cannon N2700000 viscosity standard) are discussed.

Comparison of rheological parameters of asphalt binders obtained from bending beam rheometer and dynamic shear rheometer at low temperatures

2015 ◽  
Vol 16 (sup1) ◽  
pp. 211-227 ◽  
Author(s):  
Jean-Claude Carret ◽  
Augusto Cannone Falchetto ◽  
Mihai O. Marasteanu ◽  
Hervé Di Benedetto ◽  
Michael P. Wistuba ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Asphalt Binders ◽  
Rheological Parameters ◽  
Dynamic Shear ◽  
Dynamic Shear Rheometer ◽  
Bending Beam Rheometer

Establishing Linear Viscoelastic Conditions for Asphalt Binders

2000 ◽  
Vol 1728 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Mihai O. Marasteanu ◽  
David A. Anderson
Keyword(s):  
Single Point ◽  
Superposition Principle ◽  
Asphalt Binder ◽  
Testing Procedure ◽  
Constitutive Relationship ◽  
Asphalt Binders ◽  
Direct Tension ◽  
Linear Viscoelastic Material ◽  
Frequency Domains ◽  
Linear Viscoelastic

The linear viscoelastic regime is defined in terms of the constitutive relationship between the stress and the strain. The set of equations that define the fundamental linear viscoelastic material properties in the time and frequency domains and their relationship to one another is based on the validity of the linearity principle. A material must obey two simultaneous conditions to be linear viscoelastic: the homogeneity (also called proportionality) condition and the superposition principle. On the basis of these considerations a testing procedure was developed to check linear viscoelastic conditions for tests performed on asphalt binders with the dynamic shear rheometer (DSR), the bending beam rheometer (BBR), and direct tension (DT). The testing procedure for the DSR requires performing strain sweeps and multiwave single-point tests. For the BBR, tests performed using different constant loads are required. In addition, the recovery part of the specification test is recorded. For the DT, tests performed at different strain rates and relaxation tests performed at different strain levels are required. When applied to asphalt binder data, the testing procedure found no departure from viscoelastic conditions for the DSR and BBR test data. However, the DT procedure indicated a departure from linear viscoelastic conditions.

Creep Model Based on Theta Projection and Omega Method for Predicting the Creep Behavior of Alloy

2007 ◽  
Vol 353-358 ◽  
pp. 533-536
Author(s):  
Bong Min Song ◽  
Jong Yup Kim ◽  
Joon Hyun Lee
Keyword(s):  
Creep Behavior ◽  
Constant Load ◽  
Control Mode ◽  
Creep Model ◽  
Test Results ◽  
Creep Data ◽  
Creep Tests ◽  
Omega Method ◽  
Improved Model ◽  
Term Creep

Creep testing of Alloy 718 has been carried out at various loads in the temperature range near 650°C in constant load control mode in order to understand how to predict the creep behavior including tertiary creep. The test results have been used for evaluating the existed models, such as Theta projection and Omega method that have been widely used for predicting long term creep strain and rupture time. After determining variables and material parameters of each method with the test results, estimated creep data from each model have been compared with the each measured creep data from the creep tests. The root cause of the discrepancy between estimated and measured data has been analyzed in order to improve the existed methods. The reliability of the improved model has been evaluated in relation to creep data.

scholarly journals Study on Nonlinear Damage Creep Model for Rocks under Cyclic Loading and Unloading

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Liangliang Zhang ◽  
Xiaojian Wang
Keyword(s):  
Cyclic Loading ◽  
Superposition Principle ◽  
Three Dimensional ◽  
Creep Model ◽  
Model Parameters ◽  
Nonlinear Creep ◽  
Cyclic Loading And Unloading ◽  
In Series ◽  
Loading And Unloading ◽  
Stress States

To determine the nonlinear creep characteristics of rocks under cyclic loading and unloading conditions, a nonlinear Kelvin model and damage viscoplastic model are proposed. The models are connected in series with a linear elastic body to establish a nonlinear damage creep model. The differential damage constitutive equations of the proposed creep model under one-dimensional and three-dimensional stress states are derived based on the creep mechanics and elasticity theory. The damage and unloading creep equations are then obtained based on the superposition principle, and a simple and feasible method for determining the model parameters is determined. Finally, the step cyclic loading and unloading creep test data for lherzolite and limestone are used to verify the rationality and feasibility of the nonlinear damage creep model. The results show that the theoretical creep curves of the nonlinear damage creep model are consistent with the experimental curves which indicates that the proposed model can not only determine the creep properties of lherzolite and limestone under cyclic loading and unloading but also determine the nonlinear characteristics of rocks in the transient and steady-state creep stages and particularly within the accelerating creep stage.

scholarly journals Characterisation of Permanent Deformation Behaviour of Asphalt Mix Based on a Combined Elastic Plastic (CEP) Parameter

2021 ◽  
Vol 6 (12) ◽  
pp. 183
Author(s):  
Abhirup B. Roy-Chowdhury ◽  
Mofreh F. Saleh ◽  
Miguel Moyers-Gonzalez
Keyword(s):  
Dynamic Modulus ◽  
Deformation Behaviour ◽  
Permanent Deformation ◽  
Asphalt Mixture ◽  
Asphalt Binders ◽  
Rheological Parameters ◽  
Elastic Plastic ◽  
Major Mode ◽  
Dynamic Creep ◽  
Asphalt Mix

Permanent deformation or rutting is a major mode of failure in Hot Mix Asphalt (HMA) pavements. The binder used in the asphalt mixture plays an important role in the rutting resistance performance of the mixture. Currently, the Superpave rutting parameter and a more advanced test called multiple stress creep and recovery (MSCR) are the most widely used tests for rutting characterisation of asphalt binders. However, they both have their own merits and demerits. This study was undertaken to introduce a combined Elastic-Plastic (CEP) parameter as an additional binder rheological rutting parameters. The study also aimed at investigating the applicability and potential of this parameter to supplement the existing binder rheological parameters to characterise the properties of asphalt binder related to HMA rutting performance. Additionally, the correlations of the binder rheological parameters with the asphalt mix rutting parameters generated by the dynamic creep and the dynamic modulus tests were investigated. For the polymer-modified binders, Styrene-Butadiene-Styrene (SBS) was added to the PG 70-16 binder at two concentration levels (4, and 6% by the mass of the binder). A dense-graded HMA AC 14 was tested in the Dynamic Modulus (DM) and Dynamic Creep (DC) tests for evaluating the rutting performance. The CEP parameter was found to be much more reliable than the traditional G*/sin (δ) and the non-recoverable creep compliance (Jnr) parameters for evaluating the rutting behaviour of polymer modified asphalt binders, evident from better correlations of CEP with the asphalt mix performance. Unlike Jnr, the CEP parameter revealed a wider range of values, which is comparable with asphalt mixture test results.

Sign in / Sign up

Export Citation Format

Share Document