Asphalt Pavement Aging and Temperature Dependent Properties through a Functionally Graded Viscoelastic Model, Part-I: Development, Implementation and Verification

2009 ◽  
Vol 631-632 ◽  
pp. 47-52 ◽  
Author(s):  
Eshan V. Dave ◽  
Glaucio H. Paulino ◽  
William G. Buttlar
Keyword(s):  
Constitutive Model ◽  
Asphalt Concrete ◽  
Asphalt Pavement ◽  
Asphalt Binder ◽  
Viscoelastic Model ◽  
Maxwell Model ◽  
Climatic Conditions ◽  
Functionally Graded ◽  
Temperature Cycling ◽  
Analysis Approach

Asphalt concrete pavements are inherently graded viscoelastic structures. Oxidative aging of asphalt binder and temperature cycling due to climatic conditions are the major cause of such graded non-homogeneity. Current pavement analysis and simulation procedures either ignore or use a layered approach to account for non-homogeneities. For instance, the recently developed Mechanistic-Empirical Design Guide (MEPDG) [1], which was recently approved by the American Association of State Highway and Transportation Officials (AASHTO), employs a layered analysis approach to simulate the effects of material aging gradients through the depth of the pavement as a function of pavement age. In the current work, a graded viscoelastic model has been implemented within a numerical framework for the simulation of asphalt pavement responses under various loading conditions. A functionally graded generalized Maxwell model has been used in the development of a constitutive model for asphalt concrete to account for aging and temperature induced property gradients. The associated finite element implementation of the constitutive model incorporates the generalized iso-parametric formulation (GIF) proposed by Kim and Paulino [2], which leads to the graded viscoelastic elements proposed in this work. A solution, based on the correspondence principle, has been implemented in conjunction with the collocation method, which leads to an efficient inverse numerical transform procedure. This work is the first of a two-part paper and focuses on the development, implementation and verification of the aforementioned analysis approach for functionally graded viscoelastic systems. The follow-up paper focuses on the application of this approach.

Impaction of Climate Change on Asphalt Pavements

2013 ◽  
Vol 723 ◽  
pp. 617-622
Author(s):  
Er Hu Yan ◽  
Fu Pu Li ◽  
Rong Ma ◽  
Fei Chen
Keyword(s):  
Climate Change ◽  
Heat Wave ◽  
Asphalt Pavement ◽  
Asphalt Binder ◽  
Climatic Conditions ◽  
Extreme Heat ◽  
Asphalt Pavements ◽  
Asphalt Cement ◽  
The Past ◽  
Change Climate

Climate change is one of the most key global topics well-known in international community. Over the past decades years, the change climate and its impact on asphalt pavement in China is very obvious. Many expressways of asphalt pavement come forth severe rutting failure during only a few days of extensive, long-lasting, extreme heat wave in summer, which resulting in the change of asphalt cement specification and the selection practice of asphalt cement. So it is necessary to review climate change and its impact in the past, and forecast the probable situation in the future. The paper focuses specifically on the issue of asphalt binder selection under changing climatic conditions.

Asphalt Pavement Aging and Temperature Dependent Properties through a Functionally Graded Viscoelastic Model, Part-II: Applications

2009 ◽  
Vol 631-632 ◽  
pp. 53-58 ◽  
Author(s):  
Eshan V. Dave ◽  
William G. Buttlar ◽  
Glaucio H. Paulino
Keyword(s):  
Finite Elements ◽  
Asphalt Concrete ◽  
Viscoelastic Model ◽  
Concrete Pavement ◽  
Functionally Graded ◽  
Homogeneous Material ◽  
Concrete Pavements ◽  
Temperature Dependent Properties ◽  
Asphalt Concrete Pavement ◽  
Pavement Aging

This is the second article in a series of two papers describing simulation of functionally graded viscoelastic properties in asphalt concrete pavements. The techniques developed are applicable to other viscoelastic material systems with continuous, spatial grading of material properties. A full-depth asphalt concrete pavement has been simulated to demonstrate the applicability and importance of the graded viscoelastic analysis method. Based on the graded finite elements developed by Kim and Paulino[1], Buttlar et al. [2] used graded finite elements to determine typical responses to tire loading for an aged asphalt concrete pavement. In the current study, a similar pavement section is studied using the viscoelastic graded analysis (rather than elastic). Graded, layered and homogeneous material variations were used for a series of simulations, and the results from different approaches were compared.

Effect of Latex to Minimize the Use of Asphalt in Asphalt Concrete Wearing Course

2019 ◽  
Vol 961 ◽  
pp. 39-44
Author(s):  
Henri Siswanto
Keyword(s):  
Asphalt Concrete ◽  
Asphalt Pavement ◽  
Asphalt Binder ◽  
Renewable Resource ◽  
Binder Content ◽  
Asphalt Mixtures ◽  
Total Weight ◽  
Mineral Aggregate ◽  
Wet Process

One aspect that needs to be considered in the application of asphalt pavement is the fact that asphalt is a non-renewable resource which requires constant maintenance throughout its lifetime. Thus, developing a mix with asphalt contents reduced to the minimum is a challenge in and of itself. Latex, in this case, would seem to be potentially viable additives. The aim of this research is to investigate the effects of using latex as an additive to minimize the use of asphalt in asphalt concrete wearing courses (ACWC). Four varying amounts of latex were mixed with asphalt at 0%, 2%, 4%, and 6% of the total weight of an asphalt binder. A wet process was then employed to blend the mixtures together. Afterward, the latex-asphalt mixtures were added to an aggregate to form various mixtures ranging from 5% to 7% of the aggregate and the incremental weight of 0.5% of the latex-asphalt ACWC. For each latex-asphalt-aggregate mixes, the optimum binder content was determined based on stability, flow, Marshall quotient, voids in the mineral aggregate (VMA), voids in the mixture (VIM) and voids filled by the binder (VFB). The results of this experiment indicated that the addition of latex reduces the need for asphalt contents.

scholarly journals Comparison of Pavement Layers Responses with Considering Different Models for Asphalt Concrete Viscoelastic Properties

2013 ◽  
Vol 21 (2) ◽  
pp. 15-20 ◽  
Author(s):  
Mehdi Koohmishi
Keyword(s):  
Asphalt Concrete ◽  
Structural Model ◽  
Viscoelastic Model ◽  
Viscoelastic Behavior ◽  
Maxwell Model ◽  
Elastic Behavior ◽  
Linear Elastic ◽  
Concrete Layer ◽  
Linear Viscoelastic Behavior ◽  
Linear Viscoelastic

Abstract In this paper, a comparison between pavement responses is performed by considering two different models for the linear viscoelastic behavior of an asphalt concrete layer. Two models, the Maxwell model and the Kelvin-Voigt model, are generalized. The former is used in ABAQUS and the latter in KENLAYER. As a preliminary step, an appropriate structural model for a flexible pavement structure is developed in ABAQUS by considering linear elastic behavior for all the layers. According to this model, when the depth of a structural model is equal to 6 meters, there is a good agreement between the ABAQUS and KENLAYER results. In this model, the thickness of the pavement is equal to 30 centimeters, and the thickness of the subgrade is equal to 5.7 meters. Then, the viscoelastic behavior is considered for the asphalt concrete layer, and the results from KENLAYER and ABAQUS are compared with each other. The results indicate that the type of viscoelastic model applied to an asphalt concrete layer has a significant effect on the prediction of pavement responses and, logically, the predicted performance of a pavement.

scholarly journals A SWOT Analysis Approach for a Sustainable Transition to Renewable Energy in South Africa

2021 ◽  
Vol 13 (7) ◽  
pp. 3933
Author(s):  
Solomon E. Uhunamure ◽  
Karabo Shale
Keyword(s):  
Climate Change ◽  
South Africa ◽  
Renewable Energy ◽  
Regional Integration ◽  
Power Plants ◽  
Swot Analysis ◽  
Climatic Conditions ◽  
Policy Implications ◽  
Analysis Approach ◽  
Renewable Energy Resources

South Africa is been faced with erratic power supply, resulting in persistent load shedding due to ageing in most of its coal-fired power plants. Associated with generating electricity from fossil fuel are environmental consequences such as greenhouse emissions and climate change. On the other hand, the country is endowed with abundant renewable energy resources that can potentially ameliorate its energy needs. This article explores the viability of renewable energy using the strengths, weaknesses, opportunities and threats (SWOT) analysis approach on the key renewable potential in the country. The result indicates that geographic position, political and economic stability and policy implementation are some of the strengths. However, Government bureaucratic processes, level of awareness and high investment cost are some of the weaknesses. Several opportunities favour switching to renewable energy, and these include regional integration, global awareness on climate change and the continuous electricity demand. Some threats hindering the renewable energy sector in the country include land ownership, corruption and erratic climatic conditions. Some policy implications are suggested based on the findings of the study.

Determining Optimum Carbon Nanotubes Content for Asphalt Mixture in Road Pavements

2021 ◽  
Vol 1023 ◽  
pp. 121-126
Author(s):  
Van Bach Le ◽  
Van Phuc Le
Keyword(s):  
Carbon Nanotubes ◽  
Asphalt Pavement ◽  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Construction Cost ◽  
Asphalt Mixtures ◽  
Static Modulus ◽  
Pavement Construction ◽  
Modified Binder ◽  
Marshall Stability

Although small amount of binder in asphalt concrete mixture may commonly range from 3.5 to 5.5% of total mixture as per many international specifications, it has a significant impact on the total cost of pavement construction. Therefore, this paper investigated the effects of five carbon nanotubes contents of 0.05%, 0.1%, 0.15%, 0.2%, 0.25% by asphalt weight as an additive material for binder on performance characteristics of asphalt mixtures. Performance properties of CNTs modified asphalt mixtures were investigated through the Marshall stability (MS) test, indirect tensile (IDT) test, static modulus (SM) test, wheel tracking (WT) test. The results indicated that asphalt mixtures with CNT modified binder can improve both the rutting performance, IDT strength and marshall stability of tested asphalt mixtures significantly at higher percentages of carbon nanotubes. However, the issue that should be considered is the construction cost of asphalt pavement. Based on the asphalt pavement structural analysis and construction cost, it can be concluded that an optimum CNT content of 0.1% by asphalt weight may be used as additive for asphalt binder in asphalt mixtures.

Nonlinear semi-analytical nonlocal strain-gradient dynamic response investigation of phase-transition-induced transversely graded hierarchical viscoelastic nano/microplates

2019 ◽  
Vol 233 (15) ◽  
pp. 5388-5409 ◽  
Author(s):  
M Shariyat ◽  
F Farrokhi
Keyword(s):  
Strain Gradient ◽  
Viscoelastic Model ◽  
Functionally Graded ◽  
Special Technique ◽  
Stress And Strain ◽  
Transient Vibration ◽  
Size Dependent ◽  
Integration Schemes ◽  
Series Type ◽  
Nonlocal Strain Gradient

A functionally graded Boltzmann hierarchical viscoelastic model with both stress- and strain-gradient nonlocalities is developed and implemented to extract results that are more precise than results of Eringen's nonlocal elasticity model. The available size-dependent vibration analyses of the nano/microplates have focused on the frequency analysis and even not the time-dependent transient vibration analyses. In the present research, the forced and transient responses of the microplates are studied comprehensively, for the first time, using a three-element standard solid viscoelastic model. The studied transversely symmetric graded viscoelastic microplate and the relevant function of the material properties variations contain notable hints as well. Furthermore, the resulting new sixth-order nonlocal strain gradient integrodifferential equations are solved by a special technique that includes an analytical spatial Navier series-type solution and a trapezoidal and Runge–Kutta integration schemes, in time domain. Finally, the influences of the stress- and strain-gradient nonlocality parameters and the viscoelasticity parameters on the dynamic behaviors of the viscoelastic FGM microplates are investigated in details. Results show that the effects of the strain gradient nonlocality on the viscodynamic results may be much remarkable than those of the length scale nonlocality, in microscales.

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