Master of Science (MS), Ohio University, 2022, Civil Engineering (Engineering and Technology)

Roadway construction is challenging since it is hard to control and there are many factors that might change the quality of the resulting roadway. Pavement thickness variation is one of those factors that varies due to poor construction practices. As it was observed that the variabilities in pavement thicknesses affect the overall flexible pavement performance, this research study examined the effect of the asphalt layers thickness variability on flexible pavement structural capacity and performance. Two non- destructive testing (NDT) devices, including Ground Penetrating Radar (GPR) and Falling Weight Deflectometer (FWD) were used in this study. Layer thicknesses were obtained using both extracted field cores and GPR, while FWD was utilized to back- calculate layers moduli using deflections measured on each pavement layer. The structural capacity, represented by the effective structural number (SNeff) of each roadway section, was calculated according to the AASHTO 1993 procedures, while pavement performance was evaluated using the MEPDG software for just the thinnest (5EB) and thickest (6WB) roadway sections. Two MEPDG runs were conducted for each roadway section which includes using the planned and as constructed thicknesses. Results revealed that the structural capacity of all roadway sections had a SNeff value greater than the designed SN; values calculated ranged from 7.0 to 10.31 because each section had a subgrade modulus and total pavement thickness that varied from others. Predicted performance results showed that the runs conducted using MEPDG software passed all indicators except the thermal cracking. Even though the two roadway sections failed by thermal cracking and passed other indicators, it was found that as the thickness of the AC layer increase, the predicted performance value of all distresses and IRI will decrease. Therefore, it was concluded that the thickness variability across all tested roadway se (open full item for complete abstract)

Committee: Dr. Issam Khoury (Advisor); Dr. Shad Sargand (Committee Member); Dr. Daniel Karney (Committee Member); Dr. Mary Robbins Shreve (Committee Member) Subjects: Civil Engineering

Master of Science (MS), Ohio University, 2019, Civil Engineering (Engineering and Technology)

This thesis evaluates natural and chemically stabilized subgrade soils from five project sites throughout Ohio. Three of the five project sites were historically known to have moderate to high sulfate concentrations in the natural soils (DEF-24-2.67-W, LAK- 2-7.76-W, MRW-71-3.17-N), while the other two sites were known to have little to no sulfate levels (CLA-70-13.98-W, CLI-73-6.52-E), and were used as controls. The main objective of the study was to compare in-situ and laboratory test results to determine if there were formations of ettringite or thaumasite in the soil, which can lead to sulfate heave and premature failure of pavement. Several field tests were performed such as PSPA, FWD, LWD, DCP, and SPT. Standard soil tests were performed on natural and chemically stabilized samples, such as gran size analysis, Atterberg limits, organic content, moisture content, and pH, as well as a chemical analysis comprising of neutralization potential, sulfate concentration, and X-ray diffraction (XRD). Analysis showed no major differences of moduli for pavement or soil layers between control and non-control. Results showed that sites where sulfates were known to exist, the chemically stabilized layers had sulfate concentrations greater than 3000 ppm and the pH was just barely greater than 10, which is an indication of concern for ettringite and thaumasite formation. However, the chemical analysis did not indicate formation of either mineral, therefore all conditions were not met.

Committee: Issam Khoury (Advisor) Subjects: Civil Engineering; Geotechnology; Soil Sciences

Master of Science (MS), Ohio University, 2016, Civil Engineering (Engineering and Technology)

The Falling Weight Deflectometer (FWD) and Light Weight Deflectometer (LWD) are essential nondestructive devices used for structural evaluation and characterization of pavement layer systems. This study evaluated the performances of both devices in 99 different test sites grouped into five clusters located in eight counties in Ohio. The structural adequacy of the local roads in Ohio was assessed by conducting field tests using deflectometry and backcalculation techniques. A field research program consisting of a series of FWD and LWD tests was undertaken at the same locations to investigate local pavement performances. The deflection data obtained from test results corresponding to pavement material properties were used to estimate: in-situ stiffness layer moduli, effective structural numbers, and a range of structural coefficients for different materials utilized to widen, construct, and rehabilitate county roads in Ohio. AASHTO 1993 Guide for Design of Pavement Structures and computer software, Modulus 6.0, Evercalc 5.0 were chosen to perform the backcalculation analysis. Specifically, this study investigated the feasibility and potential use of the Prima 100 LWD as in-situ testing device on the local roads. Although the FWD device could be used for the evaluation of the county roads, the cost of the equipment is prohibitive for most local agencies. The Prima 100 LWD on the other hand proved to be reasonable and effective alternative. However, the application of Prima 100 LWD requires a methodological correlation with respect to benchmark test. Comparisons were made through comprehensive regression analyses using the SPSS software. Center and radial offset sensor deflections as well as backcalculated layer moduli, layer coefficients, and the effective structural numbers were compared. The correlation results for the layer coefficients and subgrade modulus across all test sites were improved by the Rohde method. The results demonstrated consistent relationship (open full item for complete abstract)

Committee: Shad Sargand (Advisor); Teruhisa Masada (Committee Member); Issam Khoury (Committee Member); Tatiana Savin (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

Master of Science (MS), Ohio University, 2008, Civil Engineering (Engineering and Technology)

The main objectives of this study are to investigate the actual pavement performance and the expected remaining service life of nineteen (19) asphalt concrete sections and seventeen (17) portland cement concrete sections in the State of Ohio. The thirty six (36) sections were divided into a total of twenty seven (27) projects and they were classified depending on their performance as average or excellent. The design pavement parameters, material properties, traffic loads, and traffic volumes were also considered in this study. The falling weight deflectometer test was conducted to determine the actual pavement performance whereas the mechanistic-empirical pavement design guide software was used to determine the expected remaining service life of the sections. The results obtained from the FWD and the MEPDG are shown in this study and they are consistent with the original pavement classification given to the sections.

Committee: Shad M. Sargand PhD (Advisor); Eric Steinberg PhD (Committee Member); Deborah McAvoy PhD (Committee Member); Vardges Melkonian PhD (Committee Member) Subjects: Civil Engineering; Engineering