Civil Engineering Commons^™

Low-Shrinkage Fiber-Reinforced Concrete For Infrastructure Construction And Rehabilitation, Jingjie Wei

Doctoral Dissertations

"The aim of this study is to develop two classes of low-shrinkage high-performance concrete (HPC): fiber-reinforced super workable concrete (FR-SWC) for infrastructure construction and fiber-reinforced self-consolidating concrete (FR-SCC) for repair applications. HPC with excess content of shrinkage mitigation materials (SMMs), including shrinkage-reducing admixture (SRA), superabsorbent polymer (SAP), and expansive agent (EA) has a detrimental effect on mechanical performance. These classes of HPC were optimized to reduce shrinkage, enhance mechanical properties, and improve durability. The effect of fiber type (macro synthetic fiber, MSF; 5D steel fiber, 5D; 80% 3D + 20% short steel fibers; STST), SMMs, and plastic viscosity on bond …

Comprehensive Investigation Of Using Tire-Derived Aggregate In Chip Seal Subjected To Various Traffic And Environmental Conditions, Alireza Pourhassan

Doctoral Dissertations

"Chip seal is one of the most cost- and performance-effective pavement preservation treatments commonly used in the United States. Using crumb rubber obtained from scrap tires as a partial or full replacement for mineral aggregate has been proposed as a sustainable solution to reduce the negative environmental impacts of scrap tire accumulation and excessive consumption of natural resources. However, there was no data available regarding the performance of rubberized chip seal under traffic loads and environmental conditions. An extensive study using laboratory specimens and conditioning as well as field implementation and assessments were conducted to bridge this gap. Different traffic …

A Structure From Motion Photogrammetric Method For Continuously Measuring And Tracking The Deformations Of Soils During Triaxial Testing, Xiaolong Xia

Doctoral Dissertations

"Measuring soil deformation characteristics during triaxial testing is an important part of characterizing the stress-strain behavior of both saturated and unsaturated soils. The total and local deformations and volume changes of a soil specimen are indispensable parameters that need to be measured and are of great significance for understanding volume change and shear strength characteristics of the soil. Over the past several decades, numerous efforts have been made to measure the soil deformations during triaxial testing. However, it remains a great challenge for researchers to measure the volume-changes of unsaturated soils due to the existence of the air phase.

This …

Enhanced Bioretention Modeling At The Catchment-Scale: An Integrated Drainmod-Urban And Swmm Approach, Ghada Diab

Doctoral Dissertations

Bioretention systems are increasingly being adopted in stormwater management as an effective measure to promote infiltration and restore more natural hydrology in urbanized watersheds. Given the significant financial investment in these practices, reliable bioretention models are necessary to predict the effectiveness of these practices prior to installation. One such model, DRAINMOD-Urban (DM-Urban), was recently developed to produce hydrographs with a high temporal resolution at the site-scale, showing substantial promise during initial testing. However, the dataset used for initial testing was limited, consisting of one bioretention area with minimal occasions of overflow. Additionally, DM-Urban is an input-heavy model and there is …

3d Experimental Studies Of Temperature And Crystallographic Effects On Creep And Strength In Rock Salt, Amirsalar Moslehy

Doctoral Dissertations

Salt domes utilization as storage reservoirs in the energy sector has led to extensive studies on rock salt’s mechanical and geothermal behavior. These important facilities’ safety and serviceability rely on understanding rock salt’s compressive strength and creep behavior under various loading directions, water contents, in-situ stresses, and temperatures. Despite numerous studies on rock salt’s mechanical behavior in the literature, there are still many unanswered questions about rock salt’s behavior. This dissertation was aimed at utilizing state-of-the-art experimental techniques such as 3D synchrotron micro-computed tomography (SMT) and 3D x-ray diffraction (3DXRD) along with hundreds of compression and creep experiments to enhance …

Effect Of Seawater And Temperature Upon Carbon Fiber/Vinyl Ester (Cfve) Composites And Its Constituents, Vivek Chawla

Doctoral Dissertations

An experimental and computational investigation has been carried out to: (1) develop micromechanical characterization techniques for polymeric composites and (2) evaluate the effects of seawater and temperature upon the micro- and macro-response of the carbon fiber vinyl ester composites (CF/VE). Compression properties degradation due to short-term and long-term exposure to seawater is evaluated. A 12-16 % reduction in compression strength is observed due to long-term exposure to seawater, which is attributed to a decrease in interfacial shear strength (IFSS) due to long-term exposure to seawater. The developed Push-out methodology is used to characterize the IFSS. The presented approach consistently yields …

Functional Cementitious Composites With Micro-Sized Particulate Fillers For Additive Construction And Energy-Efficient Buildings, Adam Brooks

Doctoral Dissertations

With a growing energy demand, the development of sustainable and energy efficient building materials is growing rapidly. Numerous researches have focused on low carbon footprint construction materials, high-performance thermal insulations, high-performance façade, and thermal energy storage. Among these, the development of functional cementitious composites has attracted significant attention due to its potential utilities in building energy reduction and decarbonatization efforts. For example, fly ash cenospheres have been used as micro-size lightweight fillers to achieve low density and thermal conductivity. The use of phase change materials (PCM) in concrete has been studied to answer energy demands. While their inclusion into concrete …

Integrated Modeling And Monitoring For A Healthy And Sustainable Building Environment, Yifang Xu

Doctoral Dissertations

The transmission of airborne diseases indoors is a significant challenge to public health. Buildings are hotspots for viral transmission, which can result in adverse effects on human health and quality of life, especially considering that individuals spend approximately 87% of their time indoors. The emergence of the COVID-19 pandemic has highlighted the importance of considering health aspects during the development of sustainable built environments. Consequently, maintaining a healthy, sustainable, and comfortable built environment represents a major challenge for facilities management teams. However, research on the infection risks associated with emerging pandemics is still in its infancy, and the effectiveness of …

Responsive Building Envelope For Grid-Interactive Efficient Buildings – Thermal Performance And Control, Yawen He

Doctoral Dissertations

The building sector accounts for 30% of total energy consumption worldwide. Responsive building envelopes (or RBEs) are one of the approaches to achieving net-zero energy and grid-interactive efficient buildings. However, research and development of RBEs are still in the early stages of technologies, simulation, control, and design. The control strategies in prior studies did not fully explore the potential of RBEs or they obtained good performance with high design and deployment costs. A low-cost strategy that does not require knowledge of complex systems is needed, while no studies have investigated online implementations of model-free control approaches for RBEs. To address …

Promoting Enhanced Decision-Making And Proactive Management For Modularization In The Construction Industry Using Risk-Based Approach, Analytical Hierarchy Process, And Graph Theory, Mohamad Abdul Nabi

Doctoral Dissertations

"Modularization is an approach that can potentially mitigate many of the current construction industry’s challenges. Despite the documented advantages of modularization, the industry is still not able to capitalize on its full potential and benefits. The latter is due to the outdated decision-making models that may not reflect the multiple factors involved in modular construction, the unique source of risks associated with modular construction methods, need for continuous improvement, and complex contractual requirements and disputes. As such, the goal is to promote the use of modularization in the construction industry by enhancing decision-making and proactive risk management. The associated objectives …

A Study On Early Age Properties Of Concrete For Precast And 3d Printing, Debalina Ghosh

Doctoral Dissertations

Concrete is the second-most consumed material, leading the global Portland cement production of 4.1 billion tons in 2020 and 5-8% of global Carbon dioxide (CO₂) emission annually. As with any other material and practice, the construction industry is also ever-changing to meet market demand, evolving technology, and resource limitation. In the case of concrete construction, one of the main concerns is the lack of automation. In the last few decades, some new construction methods have risen to address this concern. Some of these economic and successful practices are precast construction, self-compacting concrete (SCC), and 3D printing of concrete(3DPC). …

Fundamental Investigation Of Interaction Between Moisture And Asphalt-Aggregate Systems, Rui Xiao

Doctoral Dissertations

Moisture-induced damage is one of the most common forms of flexible pavement distress which directly causes or exacerbates pavement failure. The intrusion of moisture into the asphalt pavements reduces the overall mechanical properties of the locking structures and gives rise to one or more of the visible forms of distress such as raveling, stripping, permanent deformation and fatigue cracking. This doctoral study is aimed at understanding the detrimental action of water on the asphalt-aggregate systems and the damage mechanism by multi-technique investigation. A thermodynamics framework was considered to characterize the properties of asphalt mix ingredients as well as the engineering …

Lateral Response Of Cold-Formed Steel Diaphragms With Variable Sheathing, Hernan Castaneda

Doctoral Dissertations

Cold-formed steel (CFS) framed buildings and subsystems have demonstrated safe and reliable performance while under lateral and seismic loads. Combined with their structural efficiency, this makes CFS-framed buildings popular choice even in high seismic zones. However, due to the complexity in response of CFS members and their interaction in subsystem and system levels, more research needs to be conducted to better understand the overstrength in the system, as well as the contribution of non-structural components to the overall response of the building. The lateral force resisting system (LFRS) of CFS framed buildings consist primarily of shear walls and diaphragms. The …

Investigating The Blending Mechanism And Strength Development Of 100% Hot In-Place Recycled Asphalt Mixtures, Yuetan Ma

Doctoral Dissertations

The current tendency in the asphalt paving industry is to increase the utilization of recycled asphalt pavement (RAP). Hot in-place recycling (HIR) is a promising approach to consume 100% RAP from the existing pavement for pavement surface rehabilitation in the field. However, some concerns remained regarding the utilization of HIR techniques in pavement rehabilitation: 1. Whether it is cost-effective to apply the in-place recycling techniques to pavement rehabilitation compared to the conventional HMA surface milling & filling? 2. How to improve the performance of the asphalt mixtures with HIR technique? 3. How much RAP binder can be available for coating …

Deep Learning-Based Robotic Perception For Adaptive Facility Disinfection, Da Hu

Doctoral Dissertations

Hospitals, schools, airports, and other environments built for mass gatherings can become hot spots for microbial pathogen colonization, transmission, and exposure, greatly accelerating the spread of infectious diseases across communities, cities, nations, and the world. Outbreaks of infectious diseases impose huge burdens on our society. Mitigating the spread of infectious pathogens within mass-gathering facilities requires routine cleaning and disinfection, which are primarily performed by cleaning staff under current practice. However, manual disinfection is limited in terms of both effectiveness and efficiency, as it is labor-intensive, time-consuming, and health-undermining. While existing studies have developed a variety of robotic systems for disinfecting …

Wind Flow Characteristics Of Multi-Vortex Tornadoes And Their Wind Effects On Residential Houses, Yi Zhao

Doctoral Dissertations

"Tornadoes strike the USA very frequently, with an average of 1200 reports per year, and the average annual tornado-induced property loss has reached $10B. The devastation from recent tornadoes have prompted a renewed interest in better understanding tornado dynamics, their interactions with the built environment, and the performance of civil structures during tornadoes. In the past, the wind effects caused by single-vortex tornadoes have been widely studied, while the multi-vortex tornadoes were rarely considered. In fact, many previous deadly, costly tornadoes involved multiple vortices. Therefore, it is important to understand the wind flow characteristics of multi-vortex tornadoes in order to …

Enhancing Management Of Built And Natural Water And Sanitation Systems With Data Science, Nelson Da Luz

Doctoral Dissertations

In the age of the data revolution, the civil engineer can enhance the management of infrastructure systems using new techniques focused on data. This dissertation present three studies in which data science approaches are used to enhance management of water and sanitation systems in both the built and natural environments. Chapters 1 and 2 focus on improving methods for data collection relating to water quality monitoring. In Chapter 1, the efficacy of different water quality sampling program designs is evaluated as the programs relate to meeting monitoring goals. Considerations include how timing, location, and distribution system operations can affect monitoring …

Environmental Design And Optimization Of Modular Hydropower Plants, Colin Sasthav

Doctoral Dissertations

This research aimed to understand the pathways to cost-effective and sustainable low-head hydropower. Designing viable hydropower projects requires optimization across many economic, environmental, and social outcomes. However, existing run-of-river hydropower design models often focus on economic performance and customizing technologies for high-head diversion schemes. Standard modular hydropower is a new design approach that uses standardized rather than custom-designed technologies to achieve economies of scale. Oak Ridge National Laboratory established a conceptual outline for module classes based on functions, such as generation modules and fish passage modules, but further research was needed to identify how modules should be selected and operated …

Equitable Resource Allocation To Improve Safety: An Evaluation Based On Risk, Alyssa M. Ryan

Doctoral Dissertations

Transportation safety continues to be a serious issue throughout the world. Proven safety measures have been developed to increase the safety on all roadways, but have not been universally and equitably implemented due to lack of resources, inefficiencies, and understanding. Additionally, the relative level of mobility safety remains higher in certain environments than others, creating an inequitable landscape. In this dissertation, the efficiency of using local and statement resources to improve safety is investigated while controlling for level of safety risk in vulnerable environments and locations using a comprehensive approach. Several methodologies and techniques are employed and developed to examine …

Analysis And Fate Of 2,6-Dichloro-1,4-Benzoquinone In Real And Model Drinking Waters, Aarthi Mohan

Doctoral Dissertations

For many years chlorination has served as a barrier to protect human health from waterborne disease outbreaks. Chlorine is viewed as a near-universal oxidant and disinfectant, that provides a stable residual preventing microbial re-growth all the way through the consumer’s tap. Upon reaction with natural organic matter (NOM) however, it forms disinfection by-products (DBPs) many of which are potent human carcinogens and therefore have been of research interest since the 1970’s (Froese et al., 1999; Krasner et al., 2006, 1989; Richardson, 2003; Rook, 1976, 1974; Singer, 1994). The trihalomethanes (THMs) and haloacetic acids (HAAs) are the most prevalent (Krasner et …

Synergistic Effect Of Shrinkage Mitigating Strategies On Performance Of Fiber-Reinforced Cementitious Composites, Kamran Aghaee

Doctoral Dissertations

"The advantages of using shrinkage mitigating strategies to reduce shrinkage and mitigate cracking of concrete is well documented. However, the benefits and drawbacks of employing multiple strategies have not been explored. The main objective of this study is to provide insights into the mechanisms of using multiple strategies to enhance shrinkage and cracking resistance to promote the properties of high-performance cementitious composites (HPC) designated for infrastructural construction, repair, and 3D printing applications. HPC mixtures were prepared with steel and synthetic macro and microfibers, expansive agent (EA), and shrinkage reducing admixture (SRA) coupled with various curing methods e.g., internal curing using …

Strain And Temperature Measurement From Distributed Fiber Optic Sensors In Performance-Based Fire Engineering, Yanping Zhu

Doctoral Dissertations

"Strain and temperature measurement of steel and concrete structures under fires is critical to the understanding of structural performance yet historically challenging due to a significant gap in measurement science. This Ph.D. study characterizes in six parts low-cost distributed fiber optic sensors and applies them to strain, and temperature measurements based on Rayleigh and Brillouin light scattering. The first part aims to quantify the Rayleigh scattering based measurement accuracy of distributed fiber optic sensors under a heating-holding load protocol and characterize the effect of polymer coating on the sensors as the polymer softens and melts at elevated temperatures. The second …

Design And Performance Of Self-Consolidating And Thixotropic Ultra-High-Performance Concrete For Infrastructure Construction And Rehabilitation, Le Teng

Doctoral Dissertations

"The objective of this research is to develop two classes of ultra-high-performance concrete (UHPC), one with self-consolidating consistency and the other with improved thixotropy. Tailoring the rheological properties of low yield stress UHPC can improve dispersion and orientation of steel fibers used in the design of UHPC, hence enhancing the tensile and flexural properties. Similarly, improving the thixotropy of UHPC can enable unique performance for the design of thin bonded bridge deck overlay. The research investigated various thixotropy enhancing admixtures to enhance the structural build-up at rest of UHPC. A total of 16 bonded overlay slab specimens were used to …

Deep Learning-Based Surrogate Models For Post-Earthquake Damage Assessment, Xinzhe Yuan

Doctoral Dissertations

"Seismic damage assessment is a critical step to enhance community resilience in the wake of an earthquake. This study aims to develop deep learning-based surrogate models for widely used fragility curves to achieve more accurate and rapid assessment in practice. These surrogate models are based on artificial neural networks trained from the labelled ground motions whose resulting damage classes on targeted structures are determined by nonlinear time history analyses. The development of various surrogate models is progressed in four phases. In Phase I, the multilayer perceptron (MLP) is used to develop multivariate seismic classifiers with up to 50 hand-crafted intensity …

Promoting Distributed Energy Deployment And Diffusion For Sustainable Civil Infrastructure Using Multi-Agent Based Modeling And Quantitative Analytics, Gasser Ali

Doctoral Dissertations

"Distributed Solar Generation (DSG) using small-scale Photo-Voltaic (PV) is an evolving technology with increasingly growing market penetration due to its significant benefits to consumers and broader power systems. DSG is sustainable, provides reliability, and is cost-effective where solar energy is abundant. However, the increasingly growing adoption of DSG creates uncertainties in forecasting electric power demand and market behavior. It also causes concerns of a “utility death spiral”. To this end, the goal of this research is to critically analyze the diffusion and benefits of DSG in the electric power infrastructure as a complex System-of-Systems (SoS). Specifically, this dissertation addresses the …

Characterization And Utilization Of Alkali-Activated Concrete For Sustainable Infrastructures, Eslam Gomaa

Doctoral Dissertations

“This study has investigated the feasibility of using locally available fly ashes (FAs) to synthesize alkali-activated concrete (AAC) for different structural and repair applications. Using AAC made of 100% FA reduces global CO2 emissions, saves energy, and decreases raw material consumption during the production process of ordinary Portland cement. Class C FAs, sourced from Labadie, Jeffery City, Kansas City, Thomas Hill, and Sikeston power plants in the state of Missouri, were used to synthesize the AAC. Sodium silicate (SS), Na2SiO3, and sodium hydroxide (SH), NaOH were used as the alkali activators. Slag, crumb rubber, and air-entraining admixture were used as …

Corrosion Resistance Performance Investigation Of Mild Steel Bar Coated With Magnesium Phosphate Cement Paste, Fan Zhang

Doctoral Dissertations

"In this research study, the anti-corrosion mechanism of reinforcement embedded in magnesium potassium phosphate cement (MKPC) is explored. In addition, one type of additives, metakaolin, and one type of retarder, boric acid, are employed in MKPC to modify its properties in order to further investigate corrosion resistance and to achieve mass-production coating reinforcement at the work site. This coating method may be practical for some underwater construction and some traditional reinforcement concrete structures to reduce the reinforcement corrosion rate and to eventually extend service life in both repair and new construction applications.

By comparing the electrochemical properties of bare ribbed …

Use Of Cellular Concrete For Air Convection Embankment To Protect Permafrost Foundation In Cold Regions, Hanli Wu

Doctoral Dissertations

"Crushed-rock air convection embankment (ACE) has been used to mitigate thaw settlement, and pavement distresses caused by climatic extremes in permafrost regions for over three decades. However, the desired crushed rocks needed for ACE are not readily available in many areas of interior Alaska. Burdened by the need to ship suitable rocks to remote locations, the cost of constructing an ACE is often prohibitively high, which prevents its wide use in Alaska. An existing cementitious material, cellular concrete, may provide the solution.

This study intends to systematically characterize the heat transfer patterns of ACE and identify the performance benefits of …

Investigating The Interaction Between The Recycled Components And The Asphalt Binders, Plant, Lab, And Field Mixes, Eslam Deef-Allah

Doctoral Dissertations

"Modifying asphalt binders and mixes with recycled components is common practice due to their environmental and economic merits. Literature has indicated that different recycled components interact with (blend with) asphalt differently, ranging from no blending, partial blending, or full blending. The degree of blending between recycled components and virgin asphalt binders (VABs) and the exchanged components impact the performance of modified asphalt binders. However, the nature of the interaction process between the recycled components and the VABs is not fully understood. The primary objective of this study was to explore the interactions between recycled components and VABs. By understanding the …

Theoretical Determination Of The Yield Curve For Unsaturated Soils, Sara Fayek

Doctoral Dissertations

"An important step to developing a good understanding of the behavior of unsaturated soils is to adopt a formal and simple constitutive framework and to conduct high-quality and short-time experiments. Barcelona Basic Model (BBM) was the first elastoplastic constitutive model for unsaturated soils. The yield curve, which separates the elastic region from the elastoplastic region, is an important aspect of constitutive modeling for unsaturated soils. Most concepts for unsaturated soils were developed based upon the results from suction-controlled triaxial (SCTX) tests. Though, the SCTX tests on unsaturated soils are costly, time-consuming, and laborious, and their results are questionable. This study …