Measuring resistivity as a method to calculate formation factor is becoming a popular way to evaluate transport properties of concrete. Resistivity measurements are dependent on multiple factors including the resistivity of the pore solution, leaching effects, the degree of saturation of the specimen, the age of the specimen (degree of...
The production of cement and concrete results in the production of large amounts of CO₂ emissions which can have significant negative environmental impacts. Using supplementary cementing materials (SCMs) as a cement replacement is an effective solution to reduce these negative environmental impacts, as most SCMs are waste by-products from other...
Failure of a gusset plate that caused the I-35W Bridge collapse in Minneapolis, MN resulted in mandated rating of connections by the Federal Highway Administration (FHWA). Rating connections requires material properties as an input. The material properties are generally reported on the available detailed drawings for bridges. However, some bridges...
The goal of the first part of this project was to investigate the influence of aggregate source and entrained air on the transport properties of concrete. Currently, there are several ASTM standards available that provide systematic procedures to evaluate mass transport properties of concrete. ASTM C642-13 (ASTM 2013), often referred...
Directed energy deposition and laser cladding technologies are suitable advanced manufacturing techniques for applying corrosion-resistant claddings to large carbon steel components. In this work, we clad 309L stainless steel wire onto carbon steel substrates and examine the effects of cladding parameters (laser power and travel speed) on metallurgical bonding, composition,...
The most common test methods to evaluate alkali-silica reaction (ASR), the concrete prism test (CPT) and the accelerated mortar bar tests (AMBT), have limitations and are not entirely reliable in terms of predicting the performance of concrete with prevention measures under field conditions. In this study, the miniature concrete prism...
The goal of this paper is to evaluate how synthetic lubricants perform in an enclosed gearbox application when compared with a proven mineral oil. This is in an effort to improve gearbox efficiency with the desired effect of lower emissions from of improved energy output from power generation. Four liquid...
Interest in performance specifications has been growing in the civil and construction industry in the past decade. One major focus area has been on understanding how to prolong the service life of concrete structures, since repair and rehabilitation of existing infrastructure have cost many trillions of dollars. Deterioration mechanisms such...
Carbon steel, which contains mostly iron, has been widely used as reinforcement in reinforced concrete. In the alkaline environment in reinforced concrete, a thin iron oxide film, called the passive film, forms on the surface of the steel, which protects the surface from active corrosion. The exact atomic structure of...
There is renewed interest in North America for the use of calcium aluminate cement (CAC) in infrastructure repair. The interest is driven by the specialty properties that make CAC the ideal candidate for particular applications. These include rapid strength gain, even at temperatures approaching 0°C, the ability to customize fresh...
Molten salts have been targeted as a promising coolant for next generation reactors due to their high boiling point, heat capacity, and thermal conductivity. Despite these benefits, molten salt systems present unique materials compatibility issues, highlighted by the aggressive corrosion attack and dealloying typically seen on materials in these environments....
For next-generation molten salt reactors, there is a need to be able to characterize the corrosion of the molten salts contained within them. One such tool that may be used to accomplish this is a dynamic ref- erence electrode, or DRE. Here, an aqueous dynamic reference electrode (aDRE) was developed,...
High early strength (HES) concrete is becoming increasingly used to repair damaged concrete pavement sections. The use of HES concrete enables the repaired pavement to be opened to traffic within hours of placing the concrete. A common approach used for the rapid repair of concrete pavement consists of closing a...
Use of high-strength steel (HSS) reinforcing bars could provide constructability and economic benefits for the construction of structures, reducing the initial and ultimately the life-cycle cost of bridge and building structural elements. This thesis summarizes work performed in a research project on the use of HSS reinforcing bars for concrete...
The Cascadia Subduction Zone has recently been identified as a source for an impending great earthquake. The potential of a large earthquake has created widespread interest into the resiliency of lifelines within the potentially affected areas. One critical lifeline is the electrical distribution and transmission systems which relies on legacy...
Most specifications for ready-mix concrete (RMC) limit mixing time to 90 minutes and/or truck drum revolution counts (DRC) to 300 before discharge. These specifications have been in place for many years with the objective of ensuring the quality and performance of the finished concrete product. However, limited research has been...
The research presented in this thesis assessed the use of high strength steel (HSS) reinforcement for use in reinforced concrete (RC) bridge columns. HSS is not currently allowed in reinforced concrete bridge columns due to a lack of information on the material characteristics and performance information when used in RC...
Oxide growth is a common phenomenon on aluminum alloy cladding surfaces in nuclear research and test reactors. Without better understanding of oxide growth, excessive oxide build up on the cladding surface reduces heat transfer capability from fuel to coolant and causes safety concerns due to the potential cladding rupture or...
Modulation assistance is widely employed to improve chip management in turning. This process is also known as modulated turning. Modulated turning transforms continuous cutting into intermittent cutting by periodically disengaging the tool tip from the workpiece, resulting in the generation of short, easily managed chips. This novel method improves the...
Civil engineers frequently use lime to improve the mechanical properties of weak clayey soils. The production of lime is associated with significant CO₂ emissions. Sequestering carbon dioxide into the stabilized soil can effectively reduce the carbon footprint of the lime. In the presence of CO₂, unreacted lime in the stabilized...
A Cu/Fe-spinel-based oxygen carrier designed at the National Energy Technology Laboratory was studied in order to characterize its physical and chemical behavior with cyclic oxidation and reduction treatments at 800°C for applications in chemical looping combustions. Observations were made on individual particles of the oxygen carrier in-situ using a confocal...
Chloride-induced corrosion is one of the primary causes of the degradation of reinforced steel in concrete structures. Currently, the rapid chloride permeability test (RCPT) is the most specified method to determine the concrete’s resistivity to chloride ingress, thus a determining factor in assessing the durability of concrete. While it is...
The corrosion resistances of several alloys were investigated to optimize performance and cost in seawater and supercritical CO2 environments. Many alloys are prone to corrosion in seawater and/or supercritical CO2 containing impurity environments. Exposure and electrochemical experiments were conducted in both environments to evaluate alloys’ corrosion resistance. In seawater corrosion...
Structurally efficient and cost-effective solutions are needed to extend the service-life of deficient and aging highway infrastructure around the world. One critical need is to increase the flexural strength of older reinforced concrete (RC) structures to carry heavier and more frequent loads. Titanium alloy bars (TiAB) offer a new opportunity...
Aging and deficient infrastructure has become a major problem throughout the world. This is particularly evident in the case of reinforced concrete (RC) bridges. The cost of replacing these bridges is often prohibitive, thus engineers must find ways to strengthen them. Many older RC bridges predate the modern understanding of...
Alkali silica reaction (ASR) and corrosion of reinforcement are two deterioration mechanisms in reinforced concrete (RC) structures. These deterioration mechanisms can significantly damage a RC structure and reduce its service life. Supplementary cementitious materials (SCMs) are commonly used to improve the durability of RC systems containing reactive aggregate that are...
Cast-in-drilled-hole (CIDH) piles are often constructed to depths that are inaccessible to internal vibration of the concrete. Internal vibration is necessary to consolidate the concrete and, if not performed, then typically inspection pipes are necessary to detect the presence of voids in CIDH piles. Void detection is critical to assessing...
Wave energy is emerging as a new potential source for renewable energy generation. However, wave energy technology is not currently cost competitive with other more mature renewable energy sources such as wind and solar. One approach that researchers and developers are taking to reduce the cost of wave energy is...
Large numbers of reinforced concrete deck girder (RCDG) bridges were built during the highway infrastructure boom of the 1950's. The advent of standardized deformed steel reinforcing bars during this time allowed for straight bar terminations in flexural tension regions. Designers of the time terminated reinforcing bars where they were no...
Some of the next generation of small modular reactors have been designed with helically coiled steam generators integrated into the reactor vessel to enhance natural circulation. According to the developers of TASS/SMR, a one-dimensional thermal hydraulic code written to model the Korean Atomic Energy Research Institute's SMART reactor, the Žukauskas...
Water electrolysis plays a pivotal role in achieving a green hydrogen economy by sourcing electricity from intermittent renewable sources. However, the efficiency of the electrolysis process is limited by the sluggish oxygen evolution reaction (OER) kinetics, whereas the kinetics of the hydrogen evolution reaction (HER) are more facile. This thesis...
Using supercritical CO₂ (sCO₂) as a working fluid has increasingly gained attention in the energy industry. sCO₂ power cycles has various advantages, such as high cycle efficiency, compact turbomachinery, and potential zero CO₂ emission. Along with these benefits, materials degradation issues have also been emphasized in the last decade. Aqueous...
The issue of chloride-induced corrosion of reinforcing steel in concrete and its economic impacts are well-known. Chlorides that cause reinforcement corrosion can be from constituent materials used to prepare concrete or can enter the hardened concrete when the structure is exposed to chloride environments. To minimize the risk of reinforcement...
Significant progress has been made over the past 20 years in developing models to estimate the service-life of reinforced concrete systems. The basic understandings of the mechanisms that control the transport of ions and moisture in concrete systems have been well researched and models for determining corrosion initiation, specifically chloride-induced...
Internal curing is a term used to describe a process in which curing water is provided to a concrete mixture from inside the mixture. Internal curing water has typically been provided in North America mixtures by using prewetted porous materials, like fine lightweight aggregate (FLWA). Alternative materials, such as superabsorbent...
Previous research has shown that using fine lightweight aggregate (FLWA) can be a promising strategy to mitigate alkali-silica reaction (ASR) in mortar and concrete. While several possible theories were proposed by researchers, discrepancies in testing methods, materials, and supporting evidence still exist. Therefore, this study was initiated. There are two...
High-energy delayed γ-rays from photofission were demonstrated to be signatures for detection and identification of special nuclear materials. Such γ-rays were measured in between linac pulses using independent data acquisition systems. A list-mode system was developed to measure low-energy delayed γ-rays after irradiation. Photofission product yields of ²³⁸U and ²³⁹Pu...
In the field of civil infrastructure, bridge desks are typically constructed using high performance concrete (HPC). Concrete bridge decks demand qualities such as low permeability, high abrasion resistance, superior durability, and long design life. Over decades of field and laboratory experience, many HPC bridge decks have been found to be...
The constituent materials of concrete often contain chlorides. The presence of chlorides in sufficient amounts can disrupt the passive layer, also known as the passive film, that protects the reinforcing steel in concrete. This disruption can lead to premature corrosion of the reinforcing steel in concrete. To minimize the risk...