2013 Session: 653

• Constitutive Modeling of Fatigue Damage Response of Asphalt Concrete Materials
  Abstract: The fatigue damage response of asphalt concrete is modeled by proposing a damage evolution function in the context of continuum damage-healing mechanics (CDHM). The uniaxial constant strain rate test is used to experimentally identify the damage density during this test. The identified damage density is used to propose the form for the evolution of the damage density variable. It is also shown that the accurate prediction of the fatigue life of asphalt concrete requires the incorporation of the micro-damage healing effect. It is argued that the micro-damage healing can also occur during the cyclic strain controlled tests in tension. The proposed damage model is incorporated in the PANDA model that includes the Schapery’s viscoelastic model (VE), Perzyna’s viscoplastic model (VP), and the micro-damage healing model (15) (H) to simulate the fatigue damage response of asphalt concrete. The damage model is validated against an extensive experimental data including constant strain rate, cyclic displacement controlled, and cyclic stress controlled tests over a range of temperatures, strain rates, loading frequencies, and stress/strain levels/amplitudes. Model predictions show that the proposed damage model is capable of predicting the fatigue damage response of asphalt concrete subjected to different loading conditions.
  Authors: Darabi, Masoud K.; Abu Al-Rub, Rashid K.; Masad, Eyad A.; Little, Dallas N.
  Authors: Darabi, Masoud K.; Abu Al-Rub, Rashid K.; Masad, Eyad A.; Little, Dallas N.
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 653
  Paper Number: 13-1598
• Application of Semicircular Bend and Fénix Tests for Assessing Effect of Load Application Time and Temperature on Fracture Energy of Asphalt Mixtures
  Abstract: Significant progress to address this issue was made in a comprehensive research effort as part of two national pooled fund studies addressing low temperature cracking in the US. Two fracture methods were thoroughly investigated and were proposed for standardization: the Disc-Shaped Compact Tension DC(T) test and the Semi Circular Bend (SCB) test. Recently, a simpler test that combines the advantages of both DC(T) and SCB configurations has been developed and successfully used in Spain, the Fénix test. This paper presents the results from the application of SCB and Fénix tests in the assessment of fracture behavior of different types of mixtures and the effect of both loading rate and temperature have on the results obtained. The study was conducted jointly by the University of Minnesota (UM) and UPC- BarcelonaTech (UPC).
  Authors: Perez-Jimenez, Felix Edmundo; Botella Nieto, Ramon; Moon, Ki Hoon; Marasteanu, Mihai O.
  Authors: Perez-Jimenez, Felix Edmundo; Botella Nieto, Ramon; Moon, Ki Hoon; Marasteanu, Mihai O.
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 653
  Paper Number: 13-1979
• Characterization of Mode-I and Mode-II Fracture Properties of Asphalt Mixture Using Semicircular Specimen Geometry
  Abstract: Cracking in asphalt pavements causes primary failure in the pavement structure and leads to long-term durability issues that are often related to moisture damage. The fracture resistance and characteristics of asphalt materials significantly affect the service life of asphalt pavements. Numerous studies to understand asphalt fracture in pavements have typically considered only mode-I (opening) fracture, but many observations have demonstrated the significance of mode-II (sliding) fracture for a better design of pavement structures and for damage characterization of asphaltic materials. This study presents experimental and numerical efforts to characterize the mode-I and mode-II fracture properties of an asphalt mixture. To this end, semi-circular bending tests were integrated with a digital image correlation system and an extended finite element method. The integrated experimental-numerical approach attempted here shows that the mode-II fracture property is approximately three times greater than the mode-I fracture property, which clearly indicates that the mode-dependent fracture characteristics are necessary in the structural design of asphalt pavements with which multiaxial damage is usually associated.
  Authors: Im, Soohyok; Ban, Hoki; Kim, Yong-Rak
  Authors: Im, Soohyok; Ban, Hoki; Kim, Yong-Rak
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 653
  Paper Number: 13-2289
• Comparison of Uniaxial and Four-Point Bending Fatigue Tests for Asphalt Mixtures
  Abstract: The fatigue properties of asphalt mixture estimated by the different fatigue tests in the laboratory are difficult to compare with each other. One of the reasons is that for so called inhomogeneous tests which do not have a uniform stress-strain distribution, the measured stiffness is weighted overall stiffness which does not really represents the stiffness of the damage zone. For homogenous fatigue tests, the stress-strain field within the specimen is uniform in theory. In this case, the measured stiffness corresponds to a material property. It is supposed that the stiffness evolutions in the inhomogeneous tests might be described by the results from the homogenous test. In this paper, the results of uniaxial tension and compression (UT/C) fatigue test and four-point bending (4PB) fa-tigue test are described and compared. The evolutions of the stiffness and phase angle are simulated by means of the partial healing (PH) model. With the model parameters, the local stiffness for each unit volume of the beam is calculated. It is found that based on the measured overall stiffness, the classical fatigue life Nf,50 of the beam in the 4PB fatigue test is larger than that of the cylinder in the UT/C fatigue test. However, in the midsection of the beam, the local stiffness evolution is similar to that observed in the UT/C fatigue tests. Based on the local stiffness concept, the comparable fatigue lines can be obtained from the UT/C and 4PB fatigue tests.
  Authors: Li, Ning; Pronk, Adriaan; Molenaar, André; van de Ven, Martin F. C.; Wu, Shaopeng
  Authors: Li, Ning; Pronk, Adriaan; Molenaar, André; van de Ven, Martin F. C.; Wu, Shaopeng
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 653
  Paper Number: 13-2610
• Modified Paris’ Law to Predict Entire Crack Growth in Asphalt Mixtures
  Abstract: The Paris’ law is a well-known and widely used method for predicting crack growth in engineering materials. Currently most Paris’ law model forms are formulated based on the growth of a single crack, which is not in accord with the actual way in which asphalt mixtures are damaged: a multitude of cracks propagate with increasing load applications. The parameters in these Paris’ law model forms are determined either by extensive testing and curve fitting, or by collecting data from a series of different tests. In order to predict the entire crack growth in an asphalt mixture, a modified Paris’ law is proposed in this paper, which is defined using the damage density. In addition, the procedure for determining the modified Paris’ law parameters (A' and n') is simplified so that they are easily obtained from one test on one asphalt mixture specimen. The proposed modified Paris’ law is applied to twenty different types of asphalt mixtures. The result shows that A' and n' are highly correlated with each other for the materials tested. Based on this relationship, the damage density formulated in the modified Paris’ law is proven to be monotonically related to n' through a sensitivity analysis. This suggests that n' can be used directly to compare the damage density of different asphalt mixtures. Investigation on the effects of asphalt binder, air void content, and aging period on fatigue cracking in asphalt mixtures further confirms that n' is a good indicator of the tendency of the material to crack. It can be used solely in material comparison and selection in terms of fatigue cracking, and a smaller value of n' is preferred.
  Authors: Luo, Xue; Luo, Rong; Lytton, Robert Leonard
  Authors: Luo, Xue; Luo, Rong; Lytton, Robert Leonard
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 653
  Paper Number: 13-2800
• Micromechanical Analysis of Localized Stress and Strain in Thermally Loaded Restrained Asphalt Mixtures
  Abstract: Understanding the evolution of critical stresses in as asphalt mixture during thermal cooling is very important for determination of thermal cracking resistance of pavements. An experimentally calibrated multi-phase micromechanical model of asphalt mixture undergoing thermal loading and glass transition was developed in a finite element platform using actual 2D images and binder properties. Good agreement was achieved between thermal stress predictions from the micromechanical simulation and the experimentally measured thermal stress curves. Significant stress concentration was observed in the modeled asphalt mixtures in the vicinity of the aggregate interfaces due to the irregular angular aggregate geometry, t and due to the known significant difference in stiffness between the asphalt and aggregate phase, causing a stiffening effect in the binder elements in the immediate vicinity of the fully bonded binder-aggregate interface. Analysis also showed that significant localized strains occur in the binder phase of a fully restrained asphalt sample due to the gradual reorientation of aggregates under the non-uniform stress distribution on their boundary. To apply the knowledge gained from the simulations, results were used to determine average binder strain rates in pavements undergoing typical cooling rates, for possible usage in low temperature binder characterization procedures, such as the Single Edge Notch Beam (SENB).
  Authors: Tabatabaee, Hassan A.; Bahia, Hussain U.
  Authors: Tabatabaee, Hassan A.; Bahia, Hussain U.
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 653
  Paper Number: 13-2802
• Effect of Emulsion Content and Cement Loading on Cold Recycling Mixture Fracture Energy Measured Using Semicircular Bending Fracture Test
  Abstract: Cold recycling is an attractive alternative to rehabilitate asphalt concrete pavement from a cost effectiveness and sustainability standpoint. Cracking resistance is a critical property that is often not considered in the design or acceptance of cold recycling mixtures. The use of the Semi Circular Bending (SCB) fracture test with the testing parameters defined in this study provides a practical way to evaluate the cracking behavior of cold recycling mixtures. Guidance is needed to help mixture designers select proper additive types and loadings. An experimental design evaluates the effect of emulsion content and cement loading on SCB fracture energy. Results from this study are used to set minimum fracture energy thresholds when designing cold recycling mixtures.
  Authors: Charmot, Stephane; Braham, Andrew; Zheng, Kefei
  Authors: Charmot, Stephane; Braham, Andrew; Zheng, Kefei
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 653
  Paper Number: 13-2925
• Modeling and Experimental Measurements of Asphalt Mixture Fracture Properties Using Semicircular Bending Test
  Abstract: The semi-circular bending (SCB) test is becoming a more popular candidate for measuring asphalt mixtures fracture properties. It is a simple and inexpensive test, the sample preparation is straight forward, and the mode of failure in SCB samples is due to tensile stress induced by bending. The objective of this study was to investigate the feasibility of using the SCB test to quantify asphalt mixture fracture properties. Seven asphalt mixtures were tested in the laboratory. Part of the experimental program results were used to develop and calibrate an extended finite element model (XFEM) coupled with cohesive zone modeling (CZM). The XFEM-CZM model was then used to investigate crack propagation in SCB and to predict SCB simulations for experimental results not used in the calibration process. The model calibration had a very good agreement with the experimental results and the model successfully predicted the SCB testing results. Based on XFEM-CZM results the crack propagation in SCB is mainly attributed to tensile stresses.
  Authors: Mahmoud, Enad; Saadeh, Shadi; Hakimelahi, Hamed; Harvey, John
  Authors: Mahmoud, Enad; Saadeh, Shadi; Hakimelahi, Hamed; Harvey, John
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 653
  Paper Number: 13-2635
• Three-Dimensional Fracture Modeling of Epoxy Asphalt Concrete Using Heterogeneous Discrete Element Model
  Abstract: Cracking in epoxy asphalt mixture (EAM) used for steel bridge wearing course continues to be a major cause of structural and functional deterioration of this material, particularly in cold climate. Therefore, it is important to understand the complex fracture behavior of this heterogeneous mixture, which is composed of irregularly shaped and randomly distributed aggregates and mastics. A three-dimensional (3-D) fracture model independent of laboratory, based on the discrete element method (DEM), is created using a randomly-truncating algorithm to investigate the fracture behavior. A bilinear displacement-softening model is implemented into the DEM framework to simulate the crack initiation and propagation in EAM. Several experimental tests are performed to obtain input parameters of materials for numerical models. The simulation results of a single-edge notched beam test, are shown to compare favorably with experimental results and accurately capture the distributions of fracture zone and stress within the model. The modeling technique herein provides more details of the progressive cracking process in laboratory fracture test, and 3-D visualization of crack trajectories also demonstrate the influence of heterogeneity on crack path. The 3-D user-defined microstructural DEM fracture model has the potential ability to help understand various fracture mechanisms and shows a realistic cracking process of quasi-brittle materials such as EAM.
  Authors: Wang, Jiangyang; Qian, Zhendong; Wang, Linbing
  Authors: Wang, Jiangyang; Qian, Zhendong; Wang, Linbing
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 653
  Paper Number: 13-2994
• Fatigue Properties of Asphalt Materials at Low In-ServiceTemperature
  Abstract: Fatigue damage is one of the most common distresses observed on the asphalt concrete pavement.To thoroughly understand the fatigue of asphalt concrete, the behaviors of the major componentsof asphalt concrete under cyclic loading are investigated in this study. A new experimentalmethod is developed to evaluate the performances of asphalt binder, mastic and fine aggregatesmixture under cyclic loading. The test results show that the fatigue performance of asphalt binderis closely related with loading magnitude, temperature and loading frequency. Mastic specimenswith varied filler content are tested and the results indicate that the mastic specimen with 30%filler content has better fatigue resistance. The micro-structure analysis of mastic and mixtureindicates that the fatigue resistance is closely related with the air void content of specimen. 3-Ddigital specimens and tests of asphalt binder, mastic and mixture are developed based on thefinite element method (FEM). With proper selection of damage model parameters, the simulationresults agree well with lab test results and can be used as a basis for future fatigue research.Finally, the reinforcement effect of basalt fiber is evaluated as an additive to improve the fatigueresistance of asphalt binding materials. It is found that with proper content, the fatigueresistances of asphalt binder and mastic are significantly improved. The numerical simulationanalysis also shows that the fiber added between fillers releases the stress concentration in theinterface area and diminishes the fatigue damage caused by cyclic loading.
  Authors: Wang, Dong; Wang, Linbing; Zhou, Guoqing; Druta, Cristian
  Authors: Wang, Dong; Wang, Linbing; Zhou, Guoqing; Druta, Cristian
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 653
  Paper Number: 13-3230
• Laboratory HMA Cracking Testing: Evaluation of Three Repeated Loading Crack Tests
  Abstract: Cracking is one of the predominant distresses occurring in hot-mix asphalt (HMA) pavements, often costing the highway agencies millions of dollars in road maintenance and rehabilitation activities. One way to minimize this distress is through material screening and selection of appropriate mix-designs that are representative of crack-resistant HMA mixes. However, there are no universally adapted standardized laboratory cracking test methods for routine mix-design and/or screening purposes for HMA mix crack-resistance. In this study, three different repeated loading cracking test methods, namely the repeated loading Overlay Tester (OTR), repeated loading indirect-tension (R-IDT), and repeated loading semicircular bending (R-SCB), were comparatively evaluated for their potential application as surrogate tests for routine crack evaluation and screening of HMA mixes in the laboratory. The evaluation criteria, based on commonly used Texas HMA mixes, included: (1) potential to readily differentiate and screen mixes, (2) sensitivity to mix-design variables such as variations in the asphalt-binder content (AC), (3) repeatability and statistical variability, (4) correlation to field performance data, and (5) practicality of implementation. Overall, the OTR test, with a proven correlation to field performance data, exhibited statistical superiority as a practical repeated loading crack test method for routine HMA mix-design and screening, seconded by the R-IDT test. However, while the R-IDT test exhibited superiority in terms of sample fabrication simplicity, validation with field data remains one of the key challenges to be addressed with this test. The R-SCB test was the least repeatable, particularly at high AC levels and appears to be better suited for low temperature testing.
  Authors: Walubita, Lubinda F.; Faruk, Abu Nayeem Md.; Alvarez, Allex E.; Izzo, Richard; Haggerty, Brett; Scullion, Tom
  Authors: Walubita, Lubinda F.; Faruk, Abu Nayeem Md.; Alvarez, Allex E.; Izzo, Richard; Haggerty, Brett; Scullion, Tom
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 653
  Paper Number: 13-3495
• Crack Propagation Model for Asphalt Mixtures Based on Cyclic Semicircular Bending Test
  Abstract: While the use of Semi-Circular Bending (SCB) test has been successful to characterize the fracture resistance of HMA, only limited attempts were found in the literature to assess the fatigue resistance of HMA in the laboratory using this geometry. The objective of this study is twofold. First, a fatigue crack propagation model was developed to predict the number of cycles to failure based on a cyclic SCB test and the generalized J-integral approach. Second, the effect of creep deformation on the SCB test results obtained at intermediate temperature was investigated. To achieve these objectives, the necessary theoretical formulation is introduced based on fracture mechanics principles. Results of the model were validated based on laboratory testing of asphalt mixtures using cyclic SCB tests. Results of this study showed good agreement between experimental and model predicted SCB test results. Based on these results, it is determined that the proposed model provides an acceptable representation of the experimental fatigue SCB test. Evaluation of the creep deformation in the monotonic SCB test showed that the average energy dissipated due to creep deformation in the SCB test was 7.1% of the total dissipated energy predicted by the model. This means that 92.9% of the energy is dissipated due to the propagation of the crack in the SCB test. Therefore, the dissipated energy due to fracture is the predominant factor controlling failure in the SCB test.
  Authors: Ying, Hao; Elseifi, Mostafa A.; Mohammad, Louay N.; Aglan, Heshmat
  Authors: Ying, Hao; Elseifi, Mostafa A.; Mohammad, Louay N.; Aglan, Heshmat
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 653
  Paper Number: 13-3515
• Fracture Energy Index Concept: Comparing Monotonic Loading Hot-Mix Asphalt Crack Tests
  Abstract:

  In this study, the concept of the Fracture Energy (FE) Index was explored as a fracture parameter to characterize and quantify the cracking resistance potential of hot-mix asphalt (HMA) mixes subjected to monotonic loading in the laboratory. Mathematically, the FE Index was defined as a parametric ratio of the total FE to the HMA tensile strength and tensile strain at peak failure load per unit crack length. The concept was put into practice by testing commonly used Texas HMA mixes, with cracking resistance potential ranging from poor to good, under the Overlay Tester -monotonic loading setup (OTM) along with two other more commonly used monotonic loading tests, namely: the Indirect Tensile Test (IDT) and the Semi-Circular Bending Test (SCB). Corresponding results indicated that the FE Index has promising potential to be used as a fracture parameter to discriminate and rank the cracking resistance potential of HMA mixes in the laboratory. As expected of monotonic loading crack tests, variability was within acceptable tolerances, except for the SCB that exhibited high variability, particularly at higher asphalt-binder contents. The FE Index also exhibited sensitivity to HMA mix-design variables such as the asphalt-binder content, particulalry for the OTM and IDT tests. Overall, the OTM and the IDT tests exhibited supperiority over the SCB test and would readily serve as surrogate crack tests for routine HMA mix-design and screening in the laboratory. The SCB test appeared to be better suited for low asphalt-binder content mixes and/or low temperature testing.

  Authors: Faruk, Abu Nayeem Md.; Walubita, Lubinda F.; Oh, Jeong Ho; Izzo, Richard; Haggerty, Brett; Scullion, Tom
  Authors: Faruk, Abu Nayeem Md.; Walubita, Lubinda F.; Oh, Jeong Ho; Izzo, Richard; Haggerty, Brett; Scullion, Tom
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 653
  Paper Number: 13-3422
• Application of Semicircular Bend and Fénix Tests for Assessing Effect of Load Application Time and Temperature on Fracture Energy of Asphalt Mixtures
  Authors: Perez-Jimenez, Felix
  Authors: Perez-Jimenez, Felix
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 653
  Paper Number: 13-1979
• Modeling and Experimental Measurements of Asphalt Mixture Fracture Properties Using Semicircular Bending Test
  Authors: Saadeh, Shadi
  Authors: Saadeh, Shadi
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 653
  Paper Number: 13-2635
• Modified Paris' Law to Predict Entire Crack Growth in Asphalt Mixtures
  Authors: Luo, Xue
  Authors: Luo, Xue
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 653
  Paper Number: 13-2800
• Micromechanical Analysis of Localized Stress and Strain in Thermally Loaded Restrained Asphalt Mixtures
  Authors: Tabatabaee, Hassan
  Authors: Tabatabaee, Hassan
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 653
  Paper Number: 13-2802
• Three-Dimensional Fracture Modeling of Epoxy Asphalt Concrete Using Heterogeneous Discrete Element Model
  Authors: Wang, Jiangyang
  Authors: Wang, Jiangyang
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 653
  Paper Number: 13-2994
• Crack Propagation Model for Asphalt Mixtures Based on Cyclic Semicircular Bending Test
  Authors: Elseifi, Mostafa
  Authors: Elseifi, Mostafa
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 653
  Paper Number: 13-3515
• Comparison of Uniaxial and Four-Point Bending Fatigue Tests for Asphalt Mixtures
  Authors: Li, Ning
  Authors: Li, Ning
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 653
  Paper Number: 13-2610
• Effect of Emulsion Content and Cement Loading on Cold Recycling Mixture Fracture Energy Measured Using Semicircular Bending Fracture Test
  Authors: Charmot, Stephane
  Authors: Charmot, Stephane
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 653
  Paper Number: 13-2925
• Effect of Emulsion Content and Cement Loading on Cold Recycling Mixture Fracture Energy Measured Using Semicircular Bending Fracture Test
  Authors: Braham, Andrew
  Authors: Braham, Andrew
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 653
  Paper Number: 13-2925