@article{keshavarzi_mocelin_kim_2022, title={A Composite Model for Predicting the Coefficient of Thermal Contraction for Asphalt Concrete Mixtures}, volume={50}, ISSN={["1945-7553"]}, DOI={10.1520/JTE2021003}, number={1}, journal={JOURNAL OF TESTING AND EVALUATION}, author={Keshavarzi, Behrooz and Mocelin, Douglas and Kim, Y. Richard}, year={2022}, month={Jan}, pages={1–23} }
 @article{keshavarzi_mocelin_kim_2021, title={Predicting Thermal Stress Restrained Specimen Test Fracture Temperatures Using the Dissipated Pseudo Strain Energy Criterion}, volume={147}, ISSN={["2573-5438"]}, DOI={10.1061/JPEODX.0000236}, abstractNote={AbstractThermal cracking is the predominant failure mode for asphalt pavements constructed in regions with severe air temperature drops or significant daily temperature variations. The thermal stre...}, number={1}, journal={JOURNAL OF TRANSPORTATION ENGINEERING PART B-PAVEMENTS}, author={Keshavarzi, Behrooz and Mocelin, Douglas and Kim, Youngsoo Richard}, year={2021}, month={Mar} }
 @article{keshavarzi_kim_2020, title={A dissipated pseudo strain energy-based failure criterion for thermal cracking and its verification using thermal stress restrained specimen tests}, volume={233}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2019.117199}, abstractNote={Low-temperature cracking is one of the most prevalent types of distress in asphalt concrete pavements in regions where the air temperature undergoes a significant daily drop. This paper proposes a failure criterion that correlates the dissipated pseudo strain energy (DPSE) at the time of failure with the reduced strain rate. Uniaxial direct tension monotonic tests, axial compression dynamic modulus tests, and direct tension cyclic fatigue tests were performed using the Asphalt Mixture Performance Tester (AMPT) for a wide range of asphalt mixtures with different reclaimed asphalt pavement (RAP) contents, binder contents, virgin binder performance grades, and aging levels. The results show that the simplified viscoelastic continuum damage (S-VECD) model, which is characterized by the dynamic modulus and cyclic fatigue test results, can predict the stress-strain behavior of a given mixture subjected to monotonic tests at different temperatures and loading rates. This finding allows the prediction of DPSE in monotonic tension tests using the S-VECD model. The thermal stress restrained specimen test (TSRST) was then used to verify the DPSE-based failure criterion and the ability of the S-VECD model to predict thermal fracture behavior. The study results show that the predicted fracture temperatures match the measured ones for the study mixtures with reasonable accuracy. The study also used data from mixtures whose RAP contents, binder contents, virgin binder grades, and aging levels were systematically altered to verify the reasonableness of the proposed procedure to evaluate the differences in thermal fracture performance that are due to changes in these factors. The ability to predict the fracture stress and fracture temperature measured via the TSRST using the S-VECD model and the suggested DPSE failure criterion is of substantial practical and technical importance because it allows the prediction of both fatigue cracking and thermal cracking using a single set of tests, i.e., AMPT dynamic modulus and cyclic fatigue tests.}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Keshavarzi, Behrooz and Kim, Y. Richard}, year={2020}, month={Feb} }
 @article{saleh_keshavarzi_rad_mocelin_elwardany_castorena_underwood_kim_2020, title={Effects of aging on asphalt mixture and pavement performance}, volume={258}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2020.120309}, abstractNote={This study investigates the effects of long-term aging on pavement performance under realistic traffic and thermal conditions. Using the NCHRP 09-54 aging procedure, a systematic study of the effects of aging on asphalt mixture linear viscoelastic and fatigue properties was conducted. The computational engine of FlexPAVE™ V1.1was modified to run more realistic pavement performance simulations. Results suggest that the effect of aging on pavement performance is evident only when simulations employ more realistic traffic and climatic conditions. In the absence of thermal conditions, the effect of changes in mixture properties on pavement performance is not significant.}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Saleh, Nooralhuda F. and Keshavarzi, Behrooz and Rad, Farhad Yousefi and Mocelin, Douglas and Elwardany, Michael and Castorena, Cassie and Underwood, B. Shane and Kim, Y. Richard}, year={2020}, month={Oct} }
 @article{wang_keshavarzi_kim_2018, title={Fatigue Performance Analysis of Pavements with RAP Using Viscoelastic Continuum Damage Theory}, volume={22}, ISSN={["1976-3808"]}, DOI={10.1007/s12205-018-2648-0}, number={6}, journal={KSCE JOURNAL OF CIVIL ENGINEERING}, author={Wang, Yizhuang David and Keshavarzi, Behrooz and Kim, Youngsoo Richard}, year={2018}, month={Jun}, pages={2118–2125} }
 @article{wang_keshavarzi_kim_2018, title={Fatigue Performance Prediction of Asphalt Pavements with FlexPAVE (TM), the S-VECD Model, and D-R Failure Criterion}, volume={2672}, ISSN={["2169-4052"]}, DOI={10.1177/0361198118756873}, abstractNote={ Reliable predictions of asphalt materials and pavement performance are important elements in mixture design, mechanistic-empirical pavement design, and performance-related specifications. This paper presents FlexPAVE™, a pavement performance prediction program. FlexPAVE™ is a three-dimensional finite element program that is capable of moving load analysis under realistic climatic conditions. It utilizes the simplified viscoelastic continuum damage (S-VECD) model to predict asphalt pavement fatigue life. This S-VECD model currently incorporates the so-called GR failure criterion to define the failure of asphalt mixtures. In this study, a new failure criterion for the S-VECD model, designated as the DR criterion, has been developed to remedy some of the shortcomings of the GR failure criterion. This DR criterion has been implemented successfully in FlexPAVETM. In this paper, FlexPAVETM is used to simulate the fatigue performance of field test sections. These test sections include various pavement structures, such as perpetual pavements and accelerated load facility test pavements in the United States, South Korea, and China, as well as various materials, such as warm-mix asphalt, reclaimed asphalt pavement, and mixtures with modified binders. The DR-based FlexPAVETM predictions have yielded good agreement with the field measurements and show more reasonable trends compared to predictions obtained using the GR failure criterion. }, number={40}, journal={TRANSPORTATION RESEARCH RECORD}, author={Wang, Yizhuang David and Keshavarzi, Behrooz and Kim, Y. Richard}, year={2018}, month={Dec}, pages={217–227} }
 @article{keshavarzi_kim_2016, title={A viscoelastic-based model for predicting the strength of asphalt. concrete in direct tension}, volume={122}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2016.06.089}, abstractNote={The modeling of asphalt concrete behavior under monotonic loading plays an important role in investigating the low temperature behavior of pavement material. Further, any proposed method should be able to consider the rate and temperature dependency of asphalt concrete. This paper presents a new method for simulating the behavior of asphalt concrete in uniaxial tension. Direct tension monotonic testing that incorporates a constant crosshead displacement rate and various temperatures was used in the experimental investigation to simulate thermal cracking of asphalt concrete. Viscoelastic continuum damage theory was applied to simulate the asphalt behavior in direct tension. This theory is able to model distributed damage within the material under both constant and dropping temperatures. A damage characteristic curve, which has been proven to represent the intrinsic property of the material, was used to simulate the damage evolution during testing. The proposed method features a single ordinary differential equation that is solved to provide the damage evolution. The results show that the predicted stress matches the measured data well for tests conducted at North Carolina State University and by other agencies. Implementing the proposed method in a finite element code provides a strong mechanistic model to predict asphalt fracture under thermal loading.}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Keshavarzi, Behrooz and Kim, Y. Richard}, year={2016}, month={Sep}, pages={721–727} }