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- Title
- Characterization of Novel Concrete Formulations: High-Volume Fly Ash for Precast Industry Use and Non-Proprietary UHPC
- Creator
- Ordillas, Kurt Andrew
- Date
- 2024
- Description
-
The use of high-volume fly ash concretes can be challenging for high-early strength applications, such as in precast construction, largely due...
Show moreThe use of high-volume fly ash concretes can be challenging for high-early strength applications, such as in precast construction, largely due to potential delays in strength gain resulting from relatively lower heats of hydration of the underlying binder formulations. Considering that the use of higher levels of available fresh or landfilled fly ash as a replacement for traditional ordinary Portland cement (OPC) could result in more sustainable mix designs, a framework to develop novel, high-volume fly ash mixes with optimized dosages of commercial grade gypsum and accelerating admixtures to enhance early-age strength performance. Early-age mechanical properties such as compressive strength, modulus of rupture, and modulus of elasticity were evaluated starting within 24 hours of specimen preparation. Experimental test results were then characterized and subsequently analyzed relative to current design provisions to highlight the best performing trial mixes (with respect to the early-age strength target) and cases where current design provisions are either unconservative or overly-conservative with respect to the test data. Additionally, thermal properties of concrete produced with fly ash were tested with two different curing environments, along with using code equations to determine if high volume fly ash provides a higher thermal resistance compared to OPC concrete. Wrapping up cementitious replacement with non-proprietary ultra high-performance concrete (UHPC) for transportation structures. Then reproducing mixtures to ensure target compressive strength values could be reached. Followed by increasing batch size to a larger quantity using a large mixer to create full-size specimens.
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- Title
- Using High-Pressure Reverse Osmosis Technique to Desalinate Produced Water
- Creator
- Dallalzadeh Atoufi, Hossein
- Date
- 2023
- Description
-
This dissertation presents a comprehensive investigation into the use of high-pressure reverse osmosis (HPRO) to desalinate produced water (PW...
Show moreThis dissertation presents a comprehensive investigation into the use of high-pressure reverse osmosis (HPRO) to desalinate produced water (PW) in the oil and gas industry, with the aim of developing sustainable water management strategies. The study analyzes fouling mechanisms in HPRO desalination, revealing the applicability of Hermia's fouling mechanism to high-salinity waters and highlighting the negligible impact of complete pore blocking and standard pore blocking in crossflow reverse osmosis (RO) desalination. Furthermore, the research investigates ion transport through commercial polyamide thin film composite membranes using the solution-friction model, elucidating the influence of factors such as pressure, temperature, and crossflow velocity on the initial flux while minimal impact on steady-state flux is observed. The assessment of oil and gas waste discharge in water systems provides insights into potential environmental consequences, and the analysis of the behavior of per- and polyfluoroalkyl substances (PFAS) in contaminated sediments using passive sampling demonstrates the rapid uptake of shorter-chain PFAS compounds due to their lower sorption potential and faster diffusion rates. The dissertation contributes to the development of sustainable water management strategies, addressing the challenges of produced water treatment and environmental contamination in the oil and gas industry, and offers valuable information on fouling mechanisms, impacts of ion transport mechanisms, waste discharge and PFAS behavior, enabling optimized desalination processes, informed waste management practices, and a better understanding of environmental contamination issues.
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