Engineering Commons^™

Hexahydro-1,3,5-Trinitro-1,3,5-Triazine (Rdx) Reduction By Granular Zero-Valent Iron In Continuous Flow Reactor, Amalia Terracciano, Jie Ge, Agamemnon Koutsospyros, Xiaoguang Meng, Benjamin Smolinski, Per Arienti

Civil Engineering Faculty Publications

Wastewater streams containing hexahydro-1, 3, 5-trinitro-1, 3, 5-triazine (RDX) are subject to regulatory discharge regulations that require processing through industrial waste treatment. Thus, the development of easy-to-apply technologies for the treatment of RDX-laden wastewater streams is imperative. In the present study, the reduction of RDX by granular zero valent iron (GZVI) in batch and column experiments was investigated. Preliminary batch tests conducted under both oxic and anoxic conditions showed that after 3.0 hours of reaction with GZVI, RDX was mainly converted to formaldehyde (CH₂O), nitrate (NO₃ ^- ), and ammonium (NH₄ ⁺ ). Column filtration tests …

Modeling The Impact Of Traffic Conditions And Bicycle Facilities On Cyclists' On-Road Stress Levels, Àlvaro Caviedes, Miguel A. Figliozzi

Civil and Environmental Engineering Faculty Publications and Presentations

Past research efforts have shown that cyclists’ safety, stress, and comfort levels greatly affect the routes chosen by cyclists and cycling frequency. Some researchers have tried to categorize cyclists’ levels of traffic stress utilizing data that can be directly measured in the field, such as the number of motorized travel lanes, motorized vehicle travel speeds, and type of bicycle infrastructure. This research effort presents a novel approach: real-world, on-road measurements of physiological stress as cyclists travel across different types of bicycle facilities at peak and off-peak traffic times. By matching videos with stressful events, it was possible to observe the …

Prediction And Rehabilitation Of Highway Embankment Slope Failures In Changing Climate, Navid Jafari, Anand Puppala

Publications

Highway slopes constructed with clayey soil are prone to desiccation cracks due to wetting and drying weather cycle, which allows greater moisture infiltration into the embankment from precipitation. Fissures formed due to extended wetting and drying cycles allow water to seep deeper into the soil than surficial wetting and increase the water content. This increases the moisture content in the soil and results in reduction in shear strength to the fully softened strength. On the other hand, development of desiccation cracks and reduction of the soil matric suction ultimately result in higher hydraulic conductivity value which causes development of higher …

Metagenomics Reveal Triclosan-Induced Changes In The Antibiotic Resistome Of Anaerobic Digesters, M. Fujimoto, Daniel Elliott Carey, Patrick J. Mcnamara

Civil and Environmental Engineering Faculty Research and Publications

Triclosan (TCS) is a broad-spectrum antimicrobial used in a variety of consumer products. While it was recently banned from hand soaps in the US, it is still a key ingredient in a top-selling toothpaste. TCS is a hydrophobic micropollutant that is recalcitrant under anaerobic digestion thereby resulting in high TCS concentrations in biosolids. The objective of this study was to determine the impact of TCS on the antibiotic resistome and potential cross-protection in lab-scale anaerobic digesters using shotgun metagenomics. It was hypothesized that metagenomics would reveal selection for antibiotic resistance genes (ARGs) not previously found in pure culture studies or …

An Environmental Science And Engineering Framework For Combating Antimicrobial Resistance, Amy Pruden, Reinaldo E. Alcalde, Pedro J.J. Alvarez, Nicholas Ashbolt, Heather Bischel, Natalie L. Capiro, Emily Crossette, Dominic Frigon, Kassandra Grimes, Charles N. Haas, Kaoru Ikuma, Anthony D. Kappell, Timothy M. Lapara, Lee K. Kimbell, Mengyan Li, Xu Li, Patrick J. Mcnamara, Youngwoo Seo, Mark D. Sobsey, Emanuele Sozzi, Tala Navab-Daneshmand, Lutgarde Raskin, Maria Virginia Riquelme, Peter Vikesland, Krista Wigginton, Zhi Zhou

Civil and Environmental Engineering Faculty Research and Publications

On June 20, 2017, members of the environmental engineering and science (EES) community convened at the Association of Environmental Engineering and Science Professors (AEESP) Biennial Conference for a workshop on antimicrobial resistance. With over 80 registered participants, discussion groups focused on the following topics: risk assessment, monitoring, wastewater treatment, agricultural systems, and synergies. In this study, we summarize the consensus among the workshop participants regarding the role of the EES community in understanding and mitigating the spread of antibiotic resistance via environmental pathways. Environmental scientists and engineers offer a unique and interdisciplinary perspective and expertise needed for engaging with other …

Accounting For Landscape Heterogeneity Improves Spatial Predictions Of Tree Vulnerability To Drought, Amanda M. Schwantes, Anthony J. Parolari, Jennifer J. Swenson, Daniel M. Johnson, Jean-Christopher Domec, Robert B. Jackson, Norman F. Pelak, Amilcare Porporato

Civil and Environmental Engineering Faculty Research and Publications

As climate change continues, forest vulnerability to droughts and heatwaves is increasing, but vulnerability varies regionally and locally through landscape position. Also, most models used in forecasting forest responses to heat and drought do not incorporate relevant spatial processes.

In order to improve spatial predictions of tree vulnerability, we employed a nonlinear stochastic model of soil moisture dynamics accounting for landscape differences in aspect, topography and soils. Across a watershed in central Texas we modeled dynamic water stress for a dominant tree species, Juniperus ashei, and projected future dynamic water stress through the 21^st century.

Modeled dynamic water …

Strain And Damage Self-Sensing Of Basalt Fiber Reinforced Polymer Laminates Fabricated With Carbon Nanofibers/Epoxy Composites Under Tension, Yanlei Wang, Yongshuai Wang, Baolin Wan, Baoguo Han, Gaochuang Cai, Ruijuan Chang

Civil and Environmental Engineering Faculty Research and Publications

This study investigated the strain and damage self-sensing capabilities of basalt fiber reinforced polymer (BFRP) laminates fabricated with carbon nanofibers (CNFs)/epoxy composites subjected to tensile loadings. The conduction mechanisms based on the tunnel conduction and percolation conduction theories as well as the damage evolution were also explored. A compensation circuit with a half-bridge configuration was proposed. The results indicated the resistivity of the CNFs/BFRP laminates and CNFs/epoxy composites exhibited similar change rule, indicating that the conductive networks of CNFs/BFRP laminates were governed by CNFs/epoxy composites. With the increase of strain under monotonic tensile loading, the electrical resistance response could be …

Modeling Sulfate Attack In Modern Concrete For Building Sustainable And Resilient Infrastructure, Zachary Grasley

Publications

External sulfate attack is a complex phenomenon and is manifested in the form of large expansion, cracking, and spalling depending on the exposure solution and material constituent properties. Several models were developed in the past to demonstrate sulfate attack mechanisms that account for the diffusion of sulfate ions into the porous concrete and the successive deformation triggered by the chemical reaction and precipitation of expansive agents. However, none of these models accounts for the effect of the migration of solvent water from the low solute concentration solution to high solute concentration solution driven by the osmotic pressure. Osmotic pressure is …

In-Situ Mechanical Characterization For Compacted Aggregates, Douglas Cortes, Paola Bandini

Publications

The evaluation of compacted unbound aggregate layers is perhaps the most common undertaking in transportation-related projects. The assessment of compaction compliance in engineered fills, subgrades, subbases, and bases in roadways and railways is central to ensure longevity of ground transportation infrastructure. In many cases, premature failures in roadways that originate in the unbound aggregate layers can be traced back to inadequate compaction. These failures are preventable, provided the problem areas can be identified by a suitable field test during construction. The most widely used method for compaction assessment during construction is the nuclear density gauge (NDG) test. While the device …

Bridge Inspecting With Unmanned Aerial Vehicles R&D, Paul Darby, Vijaya Gopu

Publications

The project achieves through research including literature, on site interviews, and experimentation: 1) a recommendation for a UAV-based system to practically assist in routine bridge inspection work in the State of Louisiana, 2) the identification and description of advantages, disadvantages, and limitations in the use of UAVs for routing bridge inspection work in Louisiana, and 3) provided recommendations for future work. The Yuneec H520 aircraft and its E90 camera are recommended, as is the need for a boat to be included as part of the system. The recommended system has advantages in reaching portions of the bridge that are difficult …

Development Of Environmentally-Friendly Stabilization Methods For Transportation Infrastructure Based On Geopolymers, Miladin Radovic, Anand Puppala

Publications

Geopolymers (GPs) have received much attention as an eco-friendly and sustainable alternative to conventional chemical additives, since they can be processed at room temperatures from aqueous solutions by utilizing waste materials (e.g. fly ash) or abundant natural sources (e.g. clay). A collaborative research study is carried out by teams from Texas A&M University (TAMU) and University of Texas at Arlington (UTA) to investigate the effectiveness of GPs for stabilizing base and subgrade materials by considering the strength and shrink-swell characteristics. Two types of clay, obtained from the North Dallas area, were mixed with a potassium-based GP synthesized from metakaolin and …

Sustainable And Equitable Financing For Pedestrian Infrastructure Maintenance, Gregory Rowangould

Publications

In many communities, pedestrian infrastructure is discontinuous, inaccessible to those with physical disabilities, and poorly maintained. Correcting these problems would be a first step in providing infrastructure to achieve the active travel and related transportation goals of many communities. One nearly universal challenge to maintaining sidewalks in a state of good repair and addressing environmental justice concerns is an adequate, sustainable, and equitable source of funding. Municipal governments across the country maintain and repair their streets and roadways; however, most require residents to maintain and repair public sidewalks adjacent to their property. These policies are difficult to enforce and may …

Bridge Deck Overlays Using Ultra-High Performance Concrete, Craig Newtson, Brad Weldon

Publications

This study investigated the use of a locally produced ultra-high performance concrete (UHPC) as an alternative to typical overlay materials. Several bond strength tests including slant-shear, splitting tension, and direct tension tests were performed to assess the bond strength between UHPC and normal strength concrete (NSC) substrate with varying surface textures. Tests were also conducted to assess the early-age and longer-term shrinkage behavior and coefficient of thermal expansion of the UHPC as well as rapid chloride permeability testing. Good bond between UHPC and NSC substrate was observed even with inadequate surface texture. Combined shrinkage and thermal effects were investigated for …

Numerical Modeling Of Submarine Minibasin Flow And Morphodynamics, Elena Bastianon

Theses and Dissertations

Intraslope basins, or minibasins, are important morphological features of the continental slope in both modern and ancient sedimentary systems. Minibasins have an elliptical or spherical shape with a steep inlet or proximal zone followed by an almost horizontal basin floor, and an overflow zone near the downstream basin lip. These basins are filled with sediment transported by successive events of turbidity currents and other types of submarine flows. The work presented here focuses on turbidity current sedimentation in intraslope minibasins, which is often described in terms of the ‘fill-and- spill’ conceptual model. The ‘fill-and-spill’ model has been used previously to …

Characterization Of The Spatial And Temporal Changes In River Geometry And Sand Load With Field Data Analysis And 1d Numerical Modeling, Zeyad Ayoob Sulaiman

Theses and Dissertations

The quantification of the changes in channel geometry and sand load that have occurred on the Missouri River after engineering works and that characterize the Altamaha River in the fluvial-tidal transition zone is the main objective of this research. Dam construction and channelization on the Missouri River resulted in flow regulation, sediment shortage by dam reservoir trapping, channel straightening and narrowing. Quantifying the morphodynamic response of the Lower Missouri River to these engineering projects at short and long-time scales is a difficult problem that we approach with the analysis of the available field data and with the aid of a …

The Restoration Of The Nile River And Its Delta, Egypt. Numerical Modeling, Basim Mohammed Naseef Al-Zaidi

Theses and Dissertations

The construction of the High Aswan Dam significantly reduced the flood flows and the sediment supply to the Egyptian portion of the Nile River. Consequences of this changes in river hydrology are diffuse channel bed erosion in the upstream part of the river, in- channel sedimentation in the downstream part of the system, delta recession, habitat deterioration, wetlands loss, water pollution, and environmental problems. The feasibility of a Nile River-Delta restoration project with controlled flow releases and sediment augmentations at Aswan is here investigated with the aid of site-specific one-dimensional morphodynamic models. The water source for the restoration project, based …

Shear Strength Characteristics And Failure Mechanism Of Slopes In Overconsolidated Soils Of Nebraska, Hossein Bahmyari

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Geotechnical engineers deal with some challenging problems when encountering long-term slope stability in overconsolidated clays and clayey shales. One of these problems is determining a suitable method to estimate the reliable shear strength of overconsolidated clayey soils for long-term slope stability. According to Eversol (2013), one half of the counties in Nebraska have experienced slope failure in overconsolidated soils, especially in north and east Nebraska. In this research, shear strength characteristics of overconsolidated clayey soils of Nebraska is investigated in regard to long-term stability of slopes, and the failure mechanism in such soils is examined.

Undisturbed samples from boring logs …

Managing Diffuse Phosphorus At The Source Versus At The Sink, Katrina A. Macintosh, Brooke K. Mayer, Richard W. Mcdowell, Stephen M. Powers, Lawrence A. Baker, Treavor H. Boyer, Bruce E. Rittmann

Civil and Environmental Engineering Faculty Research and Publications

Judicious phosphorus (P) management is a global grand challenge and critical to achieving and maintaining water quality objectives while maintaining food production. The management of point sources has been successful in lowering P inputs to aquatic environments, but more difficult is reducing P discharges associated with diffuse sources, such as nonpoint runoff from agriculture and urban landscapes, as well as P accumulated in soils and sediments. Strategies for effective diffuse-P management are imperative. Many options are currently available, and the most cost-effective and practical choice depends on the local situation. This critical review describes how the metrics of P quantity …

Physical Modeling Of Flow Nets In Groundwater And Determination Of Hydraulic Conductivity, Hannah Nicholas, Moses Karakouzian

AANAPISI Poster Presentations

The goal of this study is to physically model the paths that water particles take through soil, and estimate hydraulic conductivity for several soil configurations. Water paths, or flow lines, are shown by injecting dye into sand contained in a rectangular acrylic glass tank with a vertical barrier in the center; water is poured on one side of the tank and a pump is used to maintain constant head loss. If flow lines are formed, a flow net is to be drawn using photos of the tank and hydraulic conductivity is to be calculated.

This project consists of four phases: …

Coir Fiber Reinforced Concrete, Jose De La Serna, Moses Karakouzian

AANAPISI Poster Presentations

This poster exhibits the testing and research done on general Portland Cement Concrete with the addition of coir (coconut) fibers as reinforcement. Using the fundamental constituents of cement (water, cement, fine and coarse aggregate) and processed coir fiber, concrete specimens were batched to test for compressive and flexural strengths (per appropriate ASTM standards). Cylindrical and rectangular beam specimens were subjected to loadings until failure occurred. The capacity and modes of failures of the specimens were observed. It was determined that:

• The addition of processed coir fibers decreases the overall strength of general Portland Cement Concrete. • The tested concrete’s …

Coupled Thermally-Enhanced Bioremediation And Renewable Energy Storage System: Conceptual Framework And Modeling Investigation, Ali Moradi, Kathleen M. Smits, Jonathan O. Sharp

Civil Engineering Faculty Publications - Archive

This paper presents a novel method to couple an environmental bioremediation system with a subsurface renewable energy storage system. This method involves treating unsaturated contaminated soil using in-situ thermally enhanced bioremediation; the thermal system is powered by renewable energy. After remediation goals are achieved, the thermal system can then be used to store renewable energy in the form of heat in the subsurface for later use. This method can be used for enhanced treatment of environmental pollutants for which temperature is considered a limiting factor. For instance, this system can be used at a wide variety of petroleum-related sites that …

Reducing Exposures Traffic-Related Air Pollution And Urban Building Design, Elliott T. Gall, Linda George

Mechanical and Materials Engineering Faculty Publications and Presentations

No abstract provided.

Evaluation Of Model Concepts To Describe Water Transport In Shallow Subsurface Soil And Across The Soil–Air Interface, Zhen Li, Jan Vanderborght, Kathleen M. Smits

Civil Engineering Faculty Publications - Archive

Soil water evaporation plays a critical role in mass and energy exchanges across the land– atmosphere interface. Although much is known about this process, there is no agreement on the best modeling approaches to determine soil water evaporation due to the complexity of the numerical modeling scenarios and lack of experimental data available to validate such models. Existing studies show numerical and experimental discrepancies in the evaporation behavior and soil water distribution in soils at various scales, driving us to revisit the key process representation in subsurface soil. Therefore, the goal of this work is to test different mathematical formulations …

Properties And Mechanisms Of Self-Sensing Carbon Nanofibers/Epoxy Composites For Structural Health Monitoring, Yanlei Wang, Yongshuai Wang, Baolin Wan, Baoguo Han, Gaochuang Cai, Zhizheng Li

Civil and Environmental Engineering Faculty Research and Publications

In this paper, carbon nanofibers (CNFs) with high aspect ratio were dispersed into epoxy matrix via mechanical stirring and ultrasonic treatment to fabricate self-sensing CNFs/epoxy composites. The mechanical, electrical and piezoresistive properties of the nanocomposites filled with different contents of CNFs were investigated. Based on the tunneling conduction and percolation conduction theories, the mechanisms of piezoresistive property of the nanocomposites were also explored. The experimental results show that adding CNFs can effectively enhance the compressive strengths and elastic moduli of the composites. The percolation threshold of the CNFs/epoxy composites is 0.186 vol% according to the modified General Effective Media Equation. …

Mechanical And Sorptivity Characteristics Of Edge-Oxidized Graphene Oxide (Eogo)-Cement Composites: Dry- And Wet-Mix Design Methods, Yousef Alharbi, Jinwoo An, Byoung Hooi Cho, Mohammad Khawaji, Wonseok Chung, Boo Hyun Nam

Civil Engineering Faculty Publications

This paper aims to investigate the effects of edge-oxidized graphene oxide nanoflakes (EOGO) on the mechanical properties and sorptivity of cement composites. The EOGO used in this study was produced by a mechanochemical process that assists the production of EOGO in large quantities at significantly reduced costs, enabling its practical use for infrastructure construction. The scope of this work includes the use of EOGO as an additive in cement composites, including cement paste and mortar. This study explores two mixing methods: The dry-mix method and the wet-mix method. The dry-mix method uses EOGO as dry powder in cement composites whereas …

Where There Is No Engineer - Designing For Community Resilience, Liam Mccarton, Sean O'Hogain

Books/Book Chapters

Where There Is No Engineer – Designing for Community Resilience” is a design initiative coordinated by the Development Technology in the Community (DTC) Research Group, Technological University Dublin (DIT) and Engineers Without Borders (EWB) Ireland.

The programme is delivered in partnership with various development partners and Engineers Ireland. It provides participants with the opportunity to learn about design, teamwork and communication through real, inspiring, sustainable and crosscultural development projects. By participating in the programme, students and professionals will have the opportunity to design creative solutions to real life development projects. This initiative formed part of the DIT team submission which …

Optical-Fiber-Based Smart Concrete Thermal Integrity Profiling: An Example Of Concrete Shaft, Ruoyu Zhong, Ruichang Guo, Wen Deng

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Concrete is currently the most widely used construction material in the world. The integrity of concrete during the pouring process could greatly affect its engineering performance. Taking advantage of heat production during the concrete curing process, we propose an optical-fiber-based thermal integrity profiling (TIP) method which can provide a comprehensive and accurate evaluation of the integrity of concrete immediately after its pouring. In this paper, we use concrete shaft as an example to conduct TIP by using the optical fiber as a temperature sensor which can obtain high spatial resolution temperature data. Our method is compared with current thermal infrared …

Rheological Properties Of Warm Mix Asphalt Binders And Warm Mix Asphalt Binders Containing Polyphosphoric Acid, Jun Liu, Kezhen Yan, Jenny Liu

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This paper presents the laboratory investigation of properties of warm mix asphalt (WMA) binders and WMA binders containing polyphosphoric acid (PPA).Two types of warm mix additives were used to produce the WMA binders. Superpave tests were carried out on original and short-term aged binders through the rotational viscometer, the dynamic shear rheometer (DSR), and the bending beam rheometer (BBR). The results indicated that the WMA binders with different warm mix additives showed different viscosity values, however, the addition of PPA remarkably increased the viscosity values of these two kinds of WMA binders used, in the present study, to a similar …

Advancing Bridge Technology, Task 10: Statistical Analysis And Modeling Of Us Concrete Highway Bridge Deck Performance -- Internal Final Report, Omar Ghonima, Thomas Schumacher, Avinash Unnikrishnan, Adam Fleischhacker

Civil and Environmental Engineering Faculty Publications and Presentations

Concrete highway bridge deck repairs represent the highest expense associated with bridge maintenance cost. In order to optimize such activities and use the available monies effectively, a solid understanding of the parameters that affect the performance of concrete bridge decks is critical. The National Bridge Inventory (NBI), perhaps the single-most comprehensive source of bridge information, gathers data on more than 600,000 bridges in all fifty states, the District of Columbia, and the Commonwealth of Puerto Rico. Focusing on concrete highway bridge deck performance, this research developed a nationwide database based on NBI data and other critical parameters that were computed …

Development Of Domain Analysis For Determining Potential Pavement Damage, Angeli Gamez, Jaime Hernandez, Hasan Ozer, Imad L. Al-Qadi

Civil and Environmental Engineering Faculty Research and Publications

A new approach for quantifying flexible pavement damage potential is proposed. The new method, domain analysis, utilizes multiaxial results from advanced finite element models to calculate the response of flexible pavements to tire loading. The output is a single scalar value, which is unique to a given pavement structure and loading configuration. The ability of the domain analysis to quantify bulk damage potential and overcome flaws of conventional approaches based on point responses is demonstrated by testing three case studies: (1) comparison of typical loading conditions of dual-tire assembly (DTA), new-generation wide-base tire (NG-WBT), and steer tire; (2) effect of …