Doctor of Philosophy (PhD), Ohio University, 2017, Civil Engineering (Engineering and Technology)

The installation of an unbonded concrete overlay (UBCO) is a widely-used rehabilitation technique by Ohio Department of Transportation (ODOT). For the most part these overlays have performed as expected. However, occasionally some UBCOs have performed below expectations, such as in Interstate 70 (I-70) in Madison County and Interstate 77 (I-77) in Washington and Noble County. A forensic study was conducted to investigate the causes of premature failures with UBCOs on I-70 and I-77. NCHRP standard procedures were reviewed and generally followed. Falling weight deflectometer (FWD) and distress survey data were collected from the field. MIT (Magnetic Imaging Tomography)-Scan2 was used to evaluate dowel misalignment. Concrete samples were taken from the field and were tested in the laboratory. HIPERPAV was used to evaluate early behavior of the Portland cement concrete. Finite element analysis was conducted using Abaqus to evaluate structural failure mechanisms. Key findings include: sections on I-70 with thicker bondbreaker delayed distress formation; and a lack of drainage led to the presence of water in the joints, which contributed to transverse cracking and corner break. Dowel bar inserter used during construction of I-77 contributed to cracking. Recommendations were made to ODOT to improve performance and prevent similar failures in the future.

Committee: Shad Sargand Ph.D. (Advisor); Teruhisa Masada Ph.D. (Committee Member); Sang-Soo Kim Ph.D. (Committee Member); Issam Khoury Ph.D. (Committee Member); Xiaoping Shen Ph.D. (Committee Member); Xiong Yu Ph.D. (Committee Member) Subjects: Civil Engineering

Master of Science (MS), Ohio University, 2014, Civil Engineering (Engineering and Technology)

Roadbeds are considered one of the most problematic components in pavement design and construction. Its engineering properties differ significantly in terms of soil composition, gradation, and strength parameters. Soil stabilization techniques have been widely used to improve the engineering properties of roadbed soils. Therefore, in order to study the effects of the stabilization of subgrade layers for pavement structures, theoretical and experimental work was carried out to study pavement responses constructed over stabilized subgrade with lime and cement. The theoretical study involved creating finite element models to study the nature of stresses and strains in the subgrade and asphalt layers when stabilized layer is used in the pavement structure. To study the durability and long term performance of chemically stabilized subgrade, FWD and DCP tests were performed on several pavement sections constructed with stabilized layer. The results from the theoretical study showed that the subgrade could be protected from being over-stressed during construction by providing a suitable stabilized layer. Results from field testing showed that the stiffness of chemically stabilized layers increases significantly over time. It also showed that it provides structural stability to the pavement constructed over stabilized subgrades. Based on these results, input parameters were recommended to MEPDG of flexible pavements.

Committee: Shad Sargand (Advisor) Subjects: Civil Engineering; Transportation

Master of Science (MS), Ohio University, 2010, Civil Engineering (Engineering and Technology)

This thesis presents a model to predict the pavement response using Falling Weight Deflectometer (FWD) deflection data for asphalt concrete (AC) pavement. Evercalc 5.0 and Elmod 6.0 were chosen to conduct the backcalculation of pavement layer moduli using FWD deflections. Everstress 5.0 was used to do the forward calculation using backcalculated layer moduli. Predicted pavement responses (tensile strain at the bottom of the AC layer) were compared to the measured pavement responses from U.S. Route 30 to check the validity and accuracy of the selected prediction model. The predicted results show a good agreement with the measured responses. A comparison between FWD and truck load conditions was also conducted. The results show that FWD can accurately simulate the magnitude and the duration of a moving single wheel load.

Committee: Shad Sargand PhD (Advisor); Sang-Soo Kim PhD (Committee Member); Deborah McAvoy PhD (Committee Member); Gaurav Sinha PhD (Committee Member) Subjects: Civil Engineering; Transportation

Doctor of Philosophy (PhD), Ohio University, 2007, Civil Engineering (Engineering)

The primary objective of this research consisted of incorporating laboratory-determined viscoelastic material properties into a three-dimensional finite element model to accurately simulate the behavior of a perpetual pavement structure subjected to vehicular loading at different pavement temperatures and vehicular speeds. With this finite element model, statistical models that were based on Falling Weight Deflectometer testing were developed to predict the structural response of a perpetual pavement. In this research, the dynamic modulus test was chosen to determine viscoelastic properties of hot-mix-asphalt materials in the laboratory. A 5-term Prony series was used to describe the viscoelastic behavior of hot-mix-asphalt materials. Resilient modulus tests were performed to measure resilient moduli of hot-mix-asphalt mixtures and subgrade soils. All these laboratory-determined material properties were inputted into the developed viscoelastic finite element model to predict pavement response. The developed viscoelastic finite element model was validated by and calibrated to field-measured pavement responses collected at the U.S. 30 perpetual pavement constructed in Wayne County, Ohio. The results demonstrated that the developed viscoelastic finite element model can predict pavement responses accurately. Parametric studies revealed that the developed viscoelastic finite element model performed better in pavement thickness design compared with perpetual-pavement-design-oriented software PerRoad which underestimated pavement responses. Layer modulus variation did not affect pavement response significantly. The ratio maximum-tensile-strain/load was independent of the axle load. The ratio maximum-tensile-strain/speed increased with decreasing in vehicular speeds. A nomograph was developed to correlate the maximum tensile strain to the pavement temperature depending on the thickness of the ODOT302 layer and the aggregate base. Finally, the developed finite element mo (open full item for complete abstract)

Committee: Shad Sargand (Advisor) Subjects: Engineering, Civil

Master of Science (MS), Ohio University, 1990, Civil Engineering (Engineering)

Rigid pavement condition evaluation using dynaflect and falling weight deflectometer measurements

Committee: Glen Hazen (Advisor) Subjects: Engineering, Civil

Master of Science (MS), Ohio University, 1995, Civil Engineering (Engineering)

Instrumentation of flexible pavement

Committee: Shad Sargand (Advisor) Subjects: Engineering, Civil

Master of Science (MS), Ohio University, 1996, Civil Engineering (Engineering)

Instrumentation for SPS-2

Committee: Shad Sargand (Advisor) Subjects: Engineering, Civil

Master of Science (MS), Ohio University, 1997, Civil Engineering (Engineering)

Performance of instrumented flexible pavement

Committee: Shad Sargand (Advisor) Subjects: Engineering, Civil

Master of Science (MS), Ohio University, 1999, Civil Engineering (Engineering)

Field performance of dowel bars

Committee: Shad Sargand (Advisor) Subjects: Engineering, Civil

Master of Science (MS), Ohio University, 1999, Civil Engineering (Engineering)

Subgrade and base variability on the Ohio SHRP test road

Committee: Shad Sargand (Advisor) Subjects: Engineering, Civil

Doctor of Philosophy, University of Akron, 2007, Civil Engineering

The static elastic moduli of pavement layers can be considered to be among the most controversial physical properties in pavement engineering. In addition, pavement analysis using the static elastic moduli of the constituting layers is widely known and accepted by engineers and practitioners due to its simplicity. Nondestructive tests are commonly performed on existing pavements to measure the surface deflections, which in turn are used to backcalculate the elastic moduli of the pavement layers. However, the accuracy of the backcalculated moduli is dependent on the backcalculation procedure and the associated seed moduli. None of the existing classical backcalculation methods can find the “actual” pavement moduli due to the theoretical limitations of the existing methods. These limitations include the convergence to local optima due to the use of seed moduli, which in turn lead to erroneous pavement moduli. The genetic algorithms can be used to optimize the search domain of the backcalculated moduli to avoid the premature convergence to local optima. The use of genetic algorithms in pavement engineering is new and no guidelines or thorough investigations have been carried out to address all the aspects and challenges associated with the backcalculation procedure using the genetic algorithms. This study can be considered as the first comprehensive work that deals with all aspects of both pavement and genetic algorithms and how to merge them. In addition, this work can be considered as the first state of the art work on the backcalculation of pavement moduli using genetic algorithms. In this study, the use of genetic algorithms has been studied thoroughly to address all the important parameters and operators that affect the backcalculation process. In addition, recommendations and findings regarding all the details needed to carry out the backcalculation process were identified and discussed thoroughly. New novel methods to study the interaction between the genetic op (open full item for complete abstract)

Committee: Pan Ernian (Advisor) Subjects: Engineering, Civil