Master of Science in Engineering, University of Akron, 2022, Civil Engineering

This paper details the research analyzing the effects of monotonic and cyclic loading on beam-end specimens with corrosion. The test consisted of 44 beam-end specimens tested in a vertical setup with a 55-kip actuator. Each step of the experimental process from specimen design, concrete cast and curing, accelerated corrosion procedure, and testing of each specimen are described in this paper. The variables that were the focus of this study were: Concrete cover (ranging from 1in to 3in), diameter size of rebar (#5, #6, and #8), presence of transverse stirrups, corrosion level (0%-20%), and the ratio of concrete cover to the diameter of the rebar. Additionally, Sajedi and Huang's (2015) bond strength model was evaluated for its accuracy in predicting the bond strength. Finally, each variable was analyzed to determine the impact they had on the failure modes (splitting or pull-out) for reinforced concrete.

Committee: Qindan Huang (Advisor); David Roke (Committee Member); Ping Yi (Committee Member) Subjects: Civil Engineering

Master of Science, University of Toledo, 2023, Civil Engineering

Beam-column joints play a critical role in transferring forces between beam and column elements and maintaining structural integrity during severe loading. While the nonlinear behaviors of beams and columns are commonly modelled in global frame analyses through the use of plastic hinges, the behavior of joints through the use of rigid end offsets is often omitted. The objective of this study is to develop an artificial neural network and derive the plastic hinge curves required for modeling beam-column joints in global frame analyses. As the first step, a feed-forward artificial neural network (FFNN) is developed to predict the shear strengths of beam-column joints. A comprehensive dataset of 598 experimental joint specimens is compiled from 153 previously published research studies. The 555 data points which passed the exploratory data analysis are used to train, test, and validate the proposed network for applicability to a wide range of input variables and joint configurations. The accuracy and reliability of the proposed FFNN were evaluated using a comprehensive set of evaluation metrics in comparison with three existing networks from the literature. The network predicted shear strength is used to derive shear stress-strain and moment-rotation curves for joint hinges. A spreadsheet tool is developed to execute the network formulations, calculate joint shear strength, and derive joint hinge curves for practical use by engineers and researchers.

Committee: Serhan Guner (Committee Chair); Luis Alexander Mata (Committee Member); Douglas Karl Nims (Committee Member) Subjects: Civil Engineering

Master of Science, The Ohio State University, 2022, Dentistry

Objectives: The aim of this in vitro study was to evaluate the tensile bond strength of two hard denture relining materials on denture bases fabricated from conventional, subtractive, and additive polymers. In addition, this study assessed the effect of a polymer to resin primer on the tensile bond strength of hard denture liners to different denture bases. Methods: A total of 120 hard relined denture base samples were fabricated, 40 per denture base group (Lucitone 199, Ivo Base CAD, and NextDent Denture 3D+). For each denture base group 20 samples were hard relined with one of two chair side hard denture liner (GC Reline, MucoHard). Among the hard reline groups, 10 of each group was primed with a composite to PMMA primer (Visio.link). All samples underwent thermocycling. The adhesive strength was evaluated through tensile testing. The surface contact angle was measured on each denture group sample to evaluate thewettability of the material. The data was analyzed using Inverse-variance weighted linear regression. Results: In this study overall the denture bases relined with MucoHard denture liner had significantly higherbond strength than the GC reline groups (P<0.016). The highest tensile bond strength was achieved by combining MucoHard denture liner and primed 3D printed denture base, followed by the non-primed conventional denture base, and non-primed milled denture base to MucoHard denture liner. The surface primer used in this study (Visio.Link primer, Bredent UK Ltd. Chesterfield, UK.) had a significant effect on the tensile bond strength of all tested groups (P<0.0003). However, the primer only positively influenced the bond strength of the 3D printed denture base to MucoHard denture liner, while the other groups were inversely affected. Conclusion: There was no significant difference in the tensile bond strength of chairside denture liners to denture bases fabricated using additive, subtractive, and conventional methods (P>0.05). The highest bond (open full item for complete abstract)

Committee: Shereen Azer (Advisor); Damian Lee (Committee Member); Scott Schricker (Committee Member) Subjects: Dentistry; Polymers

PhD, University of Cincinnati, 2022, Engineering and Applied Science: Civil Engineering

In this dissertation, the sustainability of asphalt pavements was investigated in three different aspects. The first part presents the first research study to evaluate the effect of adding different contents of recycled Polyethylene Tetraphthalate (PETE) to the asphalt binder on the rheological and mechanical properties of the modified binder as well as the agglomeration behavior between PETE and asphalt binder at macro-, micro-, and atomistic scales using Superpave rheological tests, Atomic Force Microscope (AFM) testing, and molecular dynamics (MD) simulation, respectively. Results indicated that Addition of PETE enhanced the high and intermediate temperature rheological properties of the PG 64-22 binder. The low-temperature rheological properties and resistance to cracking decreased slightly with increasing the PETE content in the binder. However, this reduction was not remarkable when adding 4%, 8%, or 10% PETE contents. AFM results indicated that the inclusion of PETE improved the stiffness properties and increased the roughness, reduced modulus, and bonding energy of the modified binders as compared to the control binder. MD simulation indicated that the molecular agglomeration between PETE and light asphalt binder components increased when increasing the PETE content, with highest RDF values indicated for 10% PETE modified binder. The second part of this dissertation presents the first study to evaluate the effects using tack coat material and other factors on the interlayer bond strength between the field constructed or laboratory prepared micro-surfacing single or double layers and existing pavement surface. The bond strength between micro-surfacing layer(s) and the existing pavement surface was measured in the laboratory using two types of pull-off tests and a torque bond strength test. Results indicated that samples with no tack coat had significantly lower bond strength than those with tack coat with at least 0.05 gsy total application rate. Furthermore, (open full item for complete abstract)

Committee: Munir Nazzal Ph.D. (Committee Member); Matthew Steiner Ph.D. (Committee Member); Nabil Nassif (Committee Member); Sara Khoshnevisan Ph.D. (Committee Member) Subjects: Engineering

Doctor of Philosophy, University of Akron, 2021, Civil Engineering

Adequate rebar-concrete bonding is crucial to ensure the reliable performance of reinforced concrete (RC) structures. Many factors (such as the concrete properties, concrete cover depth, transverse reinforcement, and the presence of corrosion) affect the bond behavior, and consequently the structural performance. This bond behavior is typically described by a bond stress-slip relationship, where there are two critical quantities: bond strength the maximum shear stress that bond can withstand, and peak slip the slippage at the interface when the bond strength is reached. It is understood that the bond deteriorates when corrosion is present and behaves differently under two distinct bond failure modes (i.e., splitting and pull-out). While many prior studies have focused on the influence of the aforementioned factors on the bond strength, the impact of the failure mode coupled with corrosion on the bond stress-slip relationship and structural performance have not been thoroughly investigated. This study is aimed to address this issue. In this study, first a probabilistic bond failure mode prediction model that considers various influencing factors including loading type and corrosion is developed in this study. This study uses the bond testing results of 132 beam-end specimens subjected to monotonic and cyclic loading and adopts classification methods to develop the prediction model, which is then used to evaluate the impact of bond behavior on the reliability of a RC beam with a lap splice. Then, multivariate nonlinear regression with all-possible subset model selection and symbolic multi-gene regression are adopted for probabilistic model development for bond strength and peak slip under the two bond failure modes considering corrosion. In particular, a comprehensive bond dataset collected from bond tests on the beam and beam-end specimens in the literature and from the experimental testing conducted in this study, and a criterion to specify the bond failure (open full item for complete abstract)

Committee: Qindan Huang (Advisor); David Roke (Committee Member); Craig Menzemer (Committee Member); Ping Yi (Committee Member); Richard Einsporn (Committee Member) Subjects: Civil Engineering; Design; Engineering; Experiments

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

Current practice related to the use of tack coat prior to application of microsurfacing varies across the states to states. Few states require the use of tack coat, assuming it will allow a proper bonding at the interface between the micro-surfacing layer and existing pavement. On the other hand, the majority of the states do not use tack coat. They believe is that the consistency of the micro-surfacing mix allows it to be spread uniformly, resulting in a proper bond at the interface. However, no research has been conducted to investigate the effectiveness of tack coat on interface bond strength between the micro-surfacing layer and the existing pavement. The objective of this study was twofold. First, a laboratory test scheme was developed to characterize the bond strength between the micro-surfacing layer and the existing pavement hot mix asphalt (HMA) surface. In order to evaluate the effectiveness of tack coat, samples were prepared in the laboratory with varying tack coat application rate. Additionally, different percentages of residual binder content were also used to study the influence of residual binder content on bond strength characteristics. Two types of bonding strength tests were used including “Pull-off” and “Torque” bonding strength test. The pull-off test was carried out using two commercially available devices: 1- Proceq DY 206 and 2- Com-Ten pull off tester. A torque device was developed in the laboratory to carry out the torque tests. Secondly, a field-testing test program was4 established which include in-situ testing of the bond strength and laboratory testing of the cores collected from the field. In both cases, proceq pull-off device and torque device were used to measure the bond strength. It was observed from the laboratory prepared samples that, the mixes with tack coat had significantly higher bond strength than mixes without tack coat. In general, Similar performance was observed for mixes with different tack coat application rate. No si (open full item for complete abstract)

Committee: Munir Nazzal (Advisor); Sang-soo Kim (Committee Member); Bhaven Naik (Committee Member); Sergio Lopez-Permouth (Committee Member) Subjects: Civil Engineering; Engineering

Doctor of Philosophy (PhD), Ohio University, 2018, Civil Engineering (Engineering and Technology)

With its superior mechanical properties and durability, ultra-high-performance concrete (UHPC) has been used as an alternative grout material to reduce longitudinal cracking and other degradation of shear keys in adjacent box beam bridges. This study evaluates UHPC shear key performance in field and laboratory investigations supplemented with high fidelity 3-dimensional finite element models (FEMs) of the complex behavior at the interface between HSC-UHPC joints. The results from the validated and calibrated FEM were used to optimize a new shear key shape, which was then experimentally tested. The parameters of primary importance to shear key performance were identified from the response data collected during the initial field study. The maximum relative displacement for all load cases was 5.9 mil, insufficient to damage the UHPC shear key interface. In the laboratory, the direct shear test showed the average maximum shear capacity for the UHPC shear key without shear reinforcement bars exceeds that previously observed for any other grout material and any shear key configuration. The direct tension test showed that the average maximum tensile stress for the UHPC-HSC specimens with a smooth interface exceeded previously reported values from the literature, even those with a rough interface. The adhesion, cohesion, and friction angle results from the direct tension tests and slant-shear tests reported in a previous study, were used to back-calculate the friction coefficients using Mohr-Coulomb theory. The FEMs simulating the direct shear, flexural, and direct tension tests were calibrated and validated with experimental results. The models, along with different shear key configurations, were used to investigate the load transfer through previously proposed connections. After comparing the simulated shear keys in terms of the maximum load capacity, an optimized shear key shape (Type OPT) design was selected to balance economy and strength. This Type OPT UHPC she (open full item for complete abstract)

Committee: Shad Sargand (Advisor); Alexei Davydov (Committee Member); Eric Steinberg (Committee Member); Michael Pollino (Committee Member); Kenneth Walsh (Committee Member); Issam Khoury (Committee Member) Subjects: Civil Engineering; Continental Dynamics; Engineering

Master of Science in Engineering, University of Akron, 2017, Civil Engineering

Corrosion of steel reinforcing bars embedded in concrete applications is a major problem all over the world. Effect of corrosion causes metal loss at sections, cracks in the concrete surrounding the reinforcing steel, spalling of cover concrete also leads to de-bonding of reinforcing bar from the concrete. Corrosion cracks in the surrounding concrete leads to loss in bond strength and finally reduce the structural strength and service life of the structure. This problem is consistently observed in structural slab bridges that are exposed to deicing salts during the winters. In the era of 1980's, black convention steel was replaced with epoxy-coated bars as a solution to prevent corrosion in bridge decks. However the advantage of using epoxy coated bars is still uncertain as the bond strength of these type of bars is a concern. Several researchers in the past have highlighted deleterious effect of corrosion on epoxy-coated bars that are damaged during handling. It is necessary to study the use of alternative reinforcing bars as means of corrosion protection in bridge deck applications. There are several corrosion resistant bars that are readily available in the market, but performance of these bars under accelerated corrosion conditions is still unclear. Six different types of bars which include, conventional black bars, epoxy-coated bars, hot dipped galvanizing bars, continuously galvanized bars, stainless steel bars and MMFX bars were studied in this thesis. The objective of this study is to investigate the effect of accelerated corrosion on bond strength of concrete. The bond between concrete and reinforcement bars play a major role in transfer of stresses from concrete to steel. However, corrosion weakens this bond, resulting in weakening of the Reinforced Concrete member. So, it was necessary to investigate the performance of CRR (Corrosion Resistant Bars) embedded in concrete and subjected to accelerated corrosion. The effect of addition of polypropylene (open full item for complete abstract)

Committee: Anil Patnaik Dr. (Advisor); T.S Srivatsan Dr. (Committee Member); Ping Yi Dr. (Committee Member) Subjects: Civil Engineering

Master of Science in Engineering, University of Akron, 2017, Civil Engineering

A typical flexible pavement structure used by the Ohio Department of Transportation (ODOT) consists of several layers, including the subgrade, aggregate base, asphalt concrete base, intermediate course, and surface course. A light application of an asphaltic material, referred to as tack coat, is commonly used between the asphalt layers to distribute the stresses between the layers. The objective of this study was to evaluate the interlayer bond strength resulting from the use of three tack coat materials (SS-1h, rubberized tack, and non-tracking tack) commonly used in Ohio. The interface bond strength of laboratory-prepared samples was measured using a specialized fixture developed by Pine Test Equipment, Inc. that allows loading the samples in shear until failure along the interface. This study investigated the effect of the specimen diameter (4-inch and 6-inch), tack coat application rate (0.04 gallon/yd2 and 0.1 gallon/yd2), testing temperature (20°C and 25°C), and loading rate (0.1 inch/min and 2 inch/min) on the interface bond strength. The rheological properties of the three tack coat materials were also evaluated in accordance with AASHTO T 59-09. The highest interface bond strength was observed for the non-tracking tack, followed by the SS-1h and the rubberized tack, which were found to have comparable bond strengths to laboratory samples prepared with no tack coat. The optimum tack coat application rate was found to be dependent on the tack coat material type and the testing conditions (i.e., testing temperature and loading rate). A decrease in the interface bond strength was observed for the rubberized tack with the increase in the tack coat application rate, while an increase in the interface bond strength was noticed for SS-1h and the non-tracking tack with the increase in the tack coat application rate. In general, comparable results were obtained using the 4-inch and the 6-inch samples. As expected, higher interface bond strength was observed (open full item for complete abstract)

Committee: Ala R. Abbas Dr. (Advisor); Junliang Tao Dr. (Committee Member); Zhe Luo Dr. (Committee Member) Subjects: Civil Engineering

MS, University of Cincinnati, 2003, Engineering : Electrical Engineering

This work describes the development of a new low temperature bonding technique for bonding silicon-silicon and thick silicon dioxide-Pyrex glass. Silicon-silicon bonding was achieved at 300 degrees centigrade with intermediate doped silicon dioxide layer (0.5-0.7 microns thick). Pyrex glass was successfully bonded to very thick silicon dioxide (2 microns thick) at 450-500 degrees centigrade. Neither type of bonding is possible with conventional bonding techniques. A novel concept using sodium doped thermal silicon dioxide intermediate layers was utilized for achieving this bonding. Sodium doped silicon dioxide was thermally grown using wet oxidation. A minute quantity of sodium chloride was mixed in deionized water during wet oxidation to dope sodium into the thermally grown oxide. With the application of heat and voltage, the electrostatic force of attraction binds the samples together. Bond strengths in the range of 1-4MPa were achieved. The author worked with silicon dioxides that were all thicker than 0.5 microns. The author explored this new concept (developed earlier at a very cursory level in this lab) and narrowed it to a greater extent. The author also worked on other bonding issues such as Coherent Porous Silicon (CPS) bonding to thick Pyrex glass samples for micro loop heat pipe packaging, metal- metal bonding utilizing intermediate glass layers and direct bonding of two thick glass substrates. The author suggests some solutions to overcome the constraints in bonding the above-mentioned samples. Finally, the author recommends further research in this novel bonding technique and also recommends some modifications to the SUSS MicroTec SB6 bonder.

Committee: Dr. H. Thurman Henderson (Advisor) Subjects:

Master of Science (MS), Ohio University, 2003, Civil Engineering (Engineering)

Ultra-High Performance Concrete (UHPC) is an emerging material in the concrete industry. It has a compressive strength 2 to 3 times greater than High Performance Concrete (HPC) and a flexural strength 2 to 6 times greater. These mechanical properties of UHPC make it ideal for prestressing applications. Before UHPC can be used in a prestressing application, bond performance between the UHPC and the prestressing strands is one of the behaviors that need to be studied further. Standard half-inch prestressing strands and half-inch oversized strands were cast into UHPC blocks with varying embedment depths. Strands were also cast into a conventional concrete block to serve as the control. Pull-out tests were performed while instrumentation measured the displacement occurring in the strands and the load being applied to the strands. The results showed that the UHPC displayed superior bond performance as compared with the conventional concrete.

Committee: Eric Steinberg (Advisor) Subjects: Engineering, Civil

Master of Sciences (Engineering), Case Western Reserve University, 2009, EMC - Mechanical Engineering

The National Aeronautics and Space Administration (NASA) is currently developing a new universal docking mechanism for future space exploration missions calledthe Low Impact Docking System (LIDS). In order to successfully mate two pressurized vehicles or structures in space, advanced seals are required at the interface to prevent the loss of breathable air to vacuum. The leading candidate LIDS main interface seal design is a composite assembly of silicone elastomer seal bulbs permanently molded into grooves in an electroless nickel-plated aluminum retainer. A composite seal of the style being developed has not been proven in a docking role in the history of manned spaceflight. High adhesive loads on the seal bulbs during undocking could potentially overcome the strength of the molded bond between the elastomer and the metal retainer. Bond failure would jeopardize the operation of the seal and docking port, and orbital debris could be liberated. The strength of the silicone-to-metal bond is a critical consideration for the new system, especially due to the presence of small areas of disbond created by the molding process. In the work presented herein, silicone- to-metal bonds of subscale seal specimens with different sizes of intentional disbond are destructively tensile tested. Tension is applied either uniformly on the entire seal circumference or locally in a single circumferential location. Bond failure due to uniform tension produces a wide scatter of observable failure modes and measured load-displacement behaviors. Although the ideal failure mode for the silicone-to- metal bond is 100% cohesive failure of the material, the highest observed cohesion amount is 20% of bond area for the uniform loading condition. Localized tension produces failure either as immediate tearing of the elastomer material outside the bond region or as complete peel-out of the seal bulb in one piece. In intentionally flawed specimens, neither load case considered shows a correlation bet (open full item for complete abstract)

Committee: Joseph Prahl PhD (Committee Chair); Iwan Alexander PhD (Committee Member); Roger Quinn PhD (Committee Member) Subjects: Aerospace Materials; Engineering; Mechanical Engineering; Polymers

Master of Science in Engineering, University of Akron, 2012, Civil Engineering

Corrosion of reinforced concrete (RC) is a major factor contributing to deterioration of structures, and billions of dollars are spent every year on the repairs of structures due to corrosion of reinforcement. While the main causes of reinforcement corrosion are carbonation and chloride attack, the deterioration of the reinforced concrete does not occur due to direct effects of these corrosive agents. Rather, the deterioration results from the pressure exerted on the concrete by the expansive corrosion products, creating stress in the concrete cover that result in surface cracking. The surface cracks allow an easy passage for the corrosive agent to reach the reinforcement, further accelerating the corrosion process. The bond between reinforcement and concrete is very important, as it enables the reinforced concrete member to carry compressive and tensile loads. However, corrosion weakens this bond and thus results in a weakening of the RC member. In the present study, the amount of reduction in the bond strength due to corrosion, the thickness of corrosion products for different levels of corrosion, and the width of cracks at steel-concrete interface and concrete surface were studied. The main objective of the research is to identify the effects of corrosion on mechanical properties (bond strength) of reinforced concrete members. Pullout tests were used for the determination of bond strength between reinforcement and concrete. A study iv was also conducted on the use of polypropylene fibers or basalt fibers as additives in the concrete mix, as an attempt to improve the performance of reinforced concrete members. It was found that uniform corrosion occurs only until the surface of the concrete cracks; thereafter, the corrosion is non-uniform. Also, the bond strength of reinforced concrete member increases with the increase in corrosion level up to critical percentage; above this percentage, the bond strength decreases with any further increase in corrosion level. Thi (open full item for complete abstract)

Committee: Anil Patnaik Dr. (Advisor); Joe Payer Dr. (Committee Member); Kallol Sett Dr. (Committee Member); William Schneider Dr. (Committee Member) Subjects: Civil Engineering