Xicheng Qi
Georgetown University
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Transportation Research Record | 2005
Ghazi Al-Khateeb; Xicheng Qi; Aroon Shenoy; Kevin Stuart; Terry M Mitchell
Field cores were taken in 1995 and 2002 from eight asphalt pavements constructed in 1993 at FHWAs pavement testing facility to evaluate in situ pavement aging. Dynamic mechanical properties of these cores were evaluated by using the Superpave® shear tester. The moduli of aged pavements were also predicted from binder, aggregate, and mixture properties with available prediction models, and the aging severity levels of all pavements were compared between the lab-measured and model-predicted. Eight pavements with two polymer-modified and six unmodified binders were evaluated in this study. Polymer-modified asphalt pavements showed comparatively lower aging than unmodified asphalt pavements. For unmodified asphalt pavements, stiffer asphalts tended to have higher aging indices. The binder aging index was found to be inversely proportional to the loading frequency, and differences between the aging indices for different binders were higher at lower frequency. Comparison of lab-measured and model-predicted bin...
Transportation Research Record | 2007
Ghazi G. Al-Khateeb; Nelson Harold Gibson; Xicheng Qi
In-depth details are provided for mechanistic analyses conducted for the asphalt pavements of the FHWA accelerated loading facility (ALF) by using available programs, including KENPAVE, WINLEA, EVERSTRS, EVERFLEX, and VESYS 5W. These pavements were constructed by using highly modified and unmodified asphalt binders. The described analyses focused on primary response under the ALF pavements. This study included multilayer elastic theory (MLET) solutions, finite element analysis, and analysis using the VESYS 5W program. Predictions of the primary response for the fatigue mode included the horizontal tensile stress and strain at the bottom of the hot-mix asphalt (HMA) layer and for the rutting mode included the vertical compressive stress and strain on top of each pavement layer. The impact of loading frequency and stress sensitivity (nonlinearity) on fatigue primary response, rutting primary response, and principal stresses was investigated. The frequency did affect the fatigue tensile stress and strain, primarily at the bottom of the HMA layer. It also affected the major and minor principal stresses, particularly at the bottom of the HMA layer. The frequency effect on the rutting compressive stress was insignificant, whereas it was considerable for the compressive strain within the HMA layer. The MLET solutions that used a linear elastic base provided reasonable predictions for the measured tensile strains for highly modified and unmodified asphalt pavements with an absolute percentage error in the range of 0% to 15% percent in most cases. The solutions of the MLET and VESYS 5W programs were capable of providing good predictions of the vertical deformation within the HMA layer that correlated well with the measured permanent deformation values.
Pavement Mechanics and Performance - GeoShanghai International ConferenceTongji UniversityShanghai Society of Civil EngineersAmerican Society of Civil EngineersGeorgia Institute of Technology, AtlantaUniversity of Kansas, LawrenceUniversity of Tennessee, KnoxvilleInternational Association of Foundation DrillingDeep Foundation InstituteSaga UniversityDelft University of Technology | 2006
Xicheng Qi; Terry Mitchell; Nelson Gibson; Tom Harman
In the summer of 2002, under a new transportation pooled fund study TPF-5(019), 12 full-scale lanes of pavements with various modified asphalts were constructed at the Federal Highway Administrations (FHWA) Pavement Testing Facility (PTF) in Virginia. The primary goal of the study is to use FHWAs two Accelerated Loading Facility (ALF) machines to validate and refine changes being proposed in the Superpave binder specification to properly grade modified asphalt binders. The study will also provide valuable data to test new features of NCHRP 1-37A Pavement Design Guide Methodology as well as other pavement technologies. During the construction, all 12 lanes were instrumented with strain gauges and survey plates. Multiple-depth deflectometers (MDDs) were installed in selected lanes. Pavement responses from both strain gauges and MDDs were measured after the construction and during the course of ALF loading in the pavement rutting and fatigue tests. This paper presents an overview of the pooled fund study, instrumentation, measured pavement responses and comparisons to the predicted responses from elastic layered solutions.
Applications of Advanced Technologies in Transportation Engineering. Eighth International ConferenceChina Academy of Transportation Engineers; American Society of Civil Engineers; China Highway and Transportation Society; China Navigation Institute; Transportation Research Board; Tsinghua University, China | 2004
Xicheng Qi; Terry Mitchell; James A. Sherwood; Michael Dallaire
A comprehensive bonding evaluation was conducted on an Ultra-Thin Whitetopping (UTW) experiment with eight full-scale pavement sections constructed with various design features. Strain responses were measured to monitor the bonding condition change during the accelerated loading. After the completion of loading, laboratory Iowa shear tests and field pull-off tests were performed to quantify the bond strength of the UTW-asphalt interface. Additional factors such as asphalt binder type, shearing direction, and the variability of the tests were also included in the evaluation.
2006 Journal of the Association of Asphalt Paving Technologists: From the Proceedings of the Technical Sessions | 2006
Adrian Andriescu; Nelson Gibson; Simon A. M. Hesp; Xicheng Qi; John S Youtcheff Jr
Archive | 2012
Nelson Gibson; Xicheng Qi; Aroon Shenoy; Ghazi G. Al-Khateeb; M. Emin Kutay; Adrian Andriescu; Kevin Stuart; Jack Youtcheff; Thomas Harman
Archive | 2005
Xicheng Qi; Aroon Shenoy; Ghazi Al-Khateeb; Nelson Gibson; Jack Youtcheff; Tom Harman
International Conference on Accelerated Pavement Testing, 2nd, 2004, Minneapolis, Minnesota, USA | 2004
Xicheng Qi; T Mitchell; Kevin Stuart; Jack Youtcheff; K Petros; Thomas Harman; Ghazi G. Al-Khateeb
10TH INTERNATIONAL CONFERENCE ON ASPHALT PAVEMENTS - AUGUST 12 TO 17, 2006, QUEBEC CITY, CANADA | 2006
Aroon Shenoy; T Mitchell; Nelson Gibson; Jack Youtcheff; Thomas Harman; Xicheng Qi; Ghazi G. Al-Khateeb
International Conference on Accelerated Pavement Testing, 2nd, 2004, Minneapolis, Minnesota, USA | 2004
T Mitchell; Kevin Stuart; Xicheng Qi; Ghazi G. Al-Khateeb; Jack Youtcheff; Thomas Harman