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Robert L Lytton – One of the best experts on this subject based on the ideXlab platform.
enhanced model for thermally induced transverse cracking of Asphalt PavementsConstruction and Building Materials, 2019Co-Authors: Meng Ling, Yu Chen, Sheng Hu, Robert L LyttonAbstract:
Abstract Thermal cracking is a non-load associated distress mode of Asphalt Pavements. Finite element models (FEM) were first introduced in this study to determine the thermally induced J-integral at the tip of thermal crack. After extensive runs of the FEM, artificial neural network models were constructed to predict the J-integral, which was used in the Paris’ law to calculate the cumulative thermal crack growth over time and thermal cracking fatigue life. Additionally, Long-term pavement performance data was collected to characterize the thermal cracking in different climatic zones. The calculated fatigue life was well correlated with the observed transverse cracking field performance.
prediction of field aging gradient in Asphalt PavementsTransportation Research Record, 2015Co-Authors: Fan Gu, Robert L LyttonAbstract:
The aging of Asphalt Pavements is a key factor that influences pavement performance. Aging can be characterized by laboratory tests and prediction models. Common aging prediction models use the change of physical or chemical properties of Asphalt binders based on regression techniques or aging reaction kinetics. The objective of this study was to develop a kinetics-based aging prediction model for the mixture modulus gradient in Asphalt Pavements to study long-term in-service aging. The proposed model was composed of three submodels for baseline modulus, surface modulus, and aging exponent to define the change of the mixture modulus with pavement depth. The model used kinetic parameters (aging activation energy and preexponential factor) of Asphalt mixtures and combined the two reaction rate periods (fast-rate and constant-rate). Laboratory-measured modulus gradients of 29 field cores at different ages were used to determine the model parameters. The laboratory testing condition was converted to the field condition at a given age and corresponding temperature by introducing the rheological activation energy to quantify the temperature dependence of field cores at each age. The end of the fast-rate period or the beginning of the constant-rate period was accurately identified to model these two periods and to determine the associated parameters separately. The results showed that the predictions matched well with the measurements and the calculated model parameters were verified. The proposed aging prediction model took into account the major factors that affect field aging speed of an Asphalt pavement, such as the binder type, aggregate type, air void content, pavement depth, aging temperature, and aging time.
Yanjing Zhao – One of the best experts on this subject based on the ideXlab platform.
evaluation method for transverse cracking in Asphalt Pavements on freewaysTransportation Research Record, 2010Co-Authors: Lan Zhou, Fujian Ni, Yanjing ZhaoAbstract:
Transverse cracking is one of the major distresses in Asphalt Pavements. The objective of this research is to establish an effective evaluation method for transverse cracking in Asphalt Pavements on China’s freeways. Two single indicators are presented that assess the key properties of transverse cracking: transverse crack spacing and transverse crack width ratio. The transverse crack condition index (TCCI) is then developed as a comprehensive evaluation index of transverse cracking in this study. The feasibility of this evaluating method was checked with the analysis of field detection data from Wu Xuan freeway in Anhui Province and two other freeways in Jiangsu Province, China. Through the introduction of an expert evaluation, the TCCI was converted to a scale from 0 to 100, and the threshold value was confirmed. Furthermore, the corresponding maintenance treatment method was determined according to the different transverse cracking condition levels. The results showed that the TCCI can make a good asse…
Richard Y Kim – One of the best experts on this subject based on the ideXlab platform.
mechanistic evaluation of fatigue cracking in Asphalt PavementsInternational Journal of Pavement Engineering, 2017Co-Authors: Amirhossein Norouzi, Richard Y KimAbstract:
AbstractOver the last several decades, significant research has been conducted to predict the fatigue cracking performance of Asphalt Pavements. Recently, the simplified viscoelastic continuum damage (S-VECD) model was developed as an efficient method of characterising the fatigue performance of Asphalt mixtures under a wide range of loading conditions. Two important material properties that can be determined from the S-VECD model are the damage characteristic curve that defines how damage evolves in a specimen and the energy-based failure criterion that defines when the specimen fails. These two material functions are unique for a given mixture regardless of temperature, mode of loading, stress/strain amplitude and loading history. This study presents the application of the Layered Viscoelastic Crirtical Distresses (LVECD) programme to predict the fatigue performance of 18 pavement sections from different locations in the United States and Canada. The capability of the LVECD programme to capture crack in…
investigation into top down cracking of Asphalt Pavements in north carolinaTransportation Research Record, 2013Co-Authors: Hong Joon Park, Richard Y KimAbstract:
Top-down cracking has become a commonly reported cracking mechanism in Asphalt Pavements worldwide. In top-down cracking, a crack initiates at the surface of an Asphalt concrete pavement and propagates to the bottom of the Asphalt pavement layer. Because the location and governing state of stress for top-down cracking are different from those for bottom-up cracking, analysis of pavement cracking performance must be robust enough to account for the complex mechanisms that are involved in top-down cracking. This study applies the viscoelastic continuum damage finite element model to the evaluation of two pavement sections in North Carolina where top-down cracking has been identified. Small specimen geometries are used to perform simplified viscoelastic continuum damage testing on individual Asphalt layers obtained from field cores. This testing model and the Fourier finite element program are used together for pavement cracking performance simulations, and the joint model uses the structure and layer materi…