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, 2013, Civil Engineering (Engineering and Technology)

This thesis studies the performance of perpetual pavement structures constructed by the Ohio Department of Transportation. The pavement responses, collected from sensors installed in three separate perpetual pavement test sections on U.S. Route 23 in Delaware, Ohio during controlled vehicle load testing, were the main analysis for the study. To complement the pavement responses, a software analysis of the test sections was performed using PerRoad. The main pavement responses measured by test section instrumentation were strain at the bottom of the asphalt layer as well as in the base layer of the asphalt structure, subgrade pressure, pavement deflection, and subgrade deflection. Pavement responses were compared with fatigue endurance thresholds in order to evaluate the longevity of the pavement test sections. Additionally, the influences of several variables, including axle configuration, speed, and tire pressure, were analyzed to further understand their effects on pavement responses. Although controlled vehicle load testing was conducted during periods of colder temperatures, it was discovered that all of the pavement responses analyzed for the three sections were less than their respective fatigue endurance thresholds. Additionally, speed and axle configuration had a significant influence on the pavement responses. As testing speeds were increased the pavement responses decreased in magnitude. Furthermore, testing utilizing a tandem axle truck with dual tires produced reduced pavement responses in comparison with testing utilizing a single axle truck with wide-based tires even though the tandem axle truck carried a greater load. Tire pressure did not have a significant effect on pavement responses recorded in lower portions of the pavement structure. The PerRoad analysis performed, using inputs corresponding to the U.S. Route 23 test sections, revealed that, in theory, all three of the test sections would have in-service lives in excess of their design (open full item for complete abstract)

Committee: Shad Sargand Dr. (Advisor); Eric Steinberg Dr. (Committee Member); Vardges Melkonian Dr. (Committee Member); Teruhisa Masada Dr. (Committee Member) Subjects: Civil Engineering; Engineering; Transportation

Master of Science (MS), Ohio University, 2013, Civil Engineering (Engineering and Technology)

This thesis explores asphalt perpetual pavement concepts by investigating existing asphalt concrete (AC) pavements in Ohio. In 2010, twenty AC pavement sites were selected as candidates for a forensic investigation in Ohio. Field distress surveys, coring, Falling Weight Deflectometer (FWD), Seismic Property Analyzer (SPA), and the Dynamic Cone Pentrometer (DCP) tests were performed; in addition, Indirect Tensile Strength (IDT) and Resilient Modulus (E) tests were performed in the laboratory. In 2012, five of those sites were selected to perform and verify the test results. The results were similar which validated the data from 2010. FWD back-calculation was used as the basis of determining the condition of the AC base layer. The data were used to calculate layer moduli by way of back-calculation from the Evercalc 5.0 program as well as tensile strain at the bottom of the AC base layer. Layer moduli and strain values were based on 9000 pound load applied to the pavement. A conservative value of 70 micro-strains was selected as the limit for perpetual asphalt pavement classification. Seven sites were classified as perpetual pavement. One site could be modified with the addition of a surface layer mix to meet perpetual standards. Two sites were classified as damaged. This study shows that field and laboratory testing can be used to classify asphalt pavement as perpetual. FWD and SPA testing were successful in correlating pavement performance. It also highlights particular features in AC pavement structures that correlate well with excellent pavement performance such as the influence of high quality base material like asphalt-treated base (ATB). The findings proved to be useful in understanding perpetual pavement through testing of existing pavement systems.

Committee: Shad Sargand (Advisor); Gayle Mitchell (Committee Member); Teruhisa Masada (Committee Member); Varges Melkonian (Committee Member) Subjects: Civil Engineering; Geotechnology; Transportation

Doctor of Philosophy (PhD), Ohio University, 2022, Civil Engineering (Engineering and Technology)

Perpetual pavement can be defined as a flexible pavement that lasts longer than 50 years by maintaining strain at the bottom of the Asphalt Concrete (AC) layer below a specified threshold called fatigue endurance limit. This goal can be achieved by designing a proper pavement thickness and underlying layers that resist pavement distresses. In this research, U.S. route 23 project in Delaware County, Ohio, was considered, which is one of the Strategic Highway Research Test roads (SHRP). This study aims to optimize the thickness of pavement layers to achieve the acceptance criterion of perpetual pavements in Ohio. A three-dimensional viscoelastic finite element model was developed to simulate perpetual pavement response under a different truck and tire configurations, pavement temperature, AC layer thicknesses, soil stabilization, traffic speed and tire pressures. The viscoelastic model was calibrated and validated using field-measured pavement responses using dynamic instrumentation gages embedded in the pavement layers during construction. The viscoelastic behavior of asphalt material was determined by following interconversion procedures using dynamic modulus test results to estimate Prony series where 9 terms of Prony series were used. The results showed that the developed viscoelastic model accurately captures and predicts pavement response in comparison to measured values. Six cases of thickness variation incorporated with five cases of temperature variation with and without subgrade stabilization were studied to optimize the thickness of perpetual pavement under loading and environmental conditions. The results showed that changing the AC base thickness has a higher impact on reducing tensile strain at the bottom of the AC layer despite changing aggregate base thickness due to stiffness difference. In addition, utilizing stabilized subgrade allows thinner pavement design by reducing tensile strain at the bottom of AC l (open full item for complete abstract)

Committee: Shad Sargand (Advisor); Issam Khoury (Committee Member); Adam Fuller (Committee Member); Bahaven Naik (Committee Member); Tao Yuan (Committee Member); Teruhisa Masada (Committee Member) Subjects: Civil Engineering

Master of Science (MS), Ohio University, 2011, Civil Engineering (Engineering and Technology)

This thesis analyzes the performance of perpetual pavements in use by the Ohio Department of Transportation. The pavement responses, collected from the Controlled Vehicle Loading Test, conducted on the perpetual section AC 664, of the WAY-30 project, were the basis of the study. The effects of several factors on the tensile strains and the loading pulse durations of the pavement, including speed, temperature, applied load, and lateral wheel offset, were evaluated. It was found that, even though the maximum longitudinal tensile strain, measured at the bottom layer of the pavement section, was greater than the recommended Fatigue Endurance Limit of 70 µε, no major distresses have appeared since the road was opened to traffic five years ago. It was also found that temperature and speed have a significant effect on the tensile strains and pulse durations. Greater strains were measured for the higher temperatures and the lower speeds, whereas greater pulse durations occurred at the lowest values of speed and temperature. Additionally, these results were compared with pavement responses predicted using the Mechanistic-Empirical approach described in the Mechanistic-Empirical Pavement Design Guide (MEPDG) and the multi-layer elastic analysis software, JULEA. The MEPDG procedure led to an over-prediction of the strain pulse durations of around 80% compared to those measured in the field. Contrarily, longitudinal tensile strains measured in the field were approximately 1.5 times those predicted using JULEA. Furthermore, an analysis of the pavement performance was conducted based on visual distress surveys and a pavement performance simulation using the MEPDG software. It was found that, according to annual inspections of the conditions of the Section AC 664, no major fatigue cracking signs have been observed in the five year operation period of the road. Additionally, according to the MEPDG simulation, the pavement design will not present significant fatigue cracking distres (open full item for complete abstract)

Committee: Shad Sargand PhD (Advisor); Deborah McAvoy PhD (Committee Member); Patricia Toledo-Torres PhD (Committee Member); Munir Nazzal PhD (Committee Member) Subjects: Civil Engineering

Master of Science (MS), Ohio University, 2007, Civil Engineering (Engineering)

Two long life pavement test sections were completed along US Route 30 in Wayne County, OH, as part of the Wooster by-pass, in the fall of 2005. This project represents a collaborative effort between the Ohio Department of Transportation (ODOT) and both the asphalt concrete paving and Portland cement concrete paving industries with the purpose of evaluating the performance of these novel pavements. The unique perpetual asphalt pavement concept is featured in one direction of the project, while a long lasting Portland cement concrete pavement was constructed in the other direction. The test pavements were instrumented for dynamic response parameters and subjected to controlled load vehicle tests. Results indicate that the asphalt concrete pavement exhibited “perpetual” characteristics under most loading conditions. Non-destructive tests and the determination of the mechanical properties also helped to evaluate the long life characteristics of the two pavement designs.

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