Transportation Engineering Commons^™

Effect Of Rheology Modification On Fiber Orientation And Dispersion In 3d-Printed Ultra-High-Performance Concrete, Haodao Li, Alfred Addai-Nimoh, Seongho Han, Kamal H. Khayat

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The extrusion process in 3D concrete printing (3DCP) facilitates horizontal alignment of steel fibers along the printing direction, thus enhancing the load-bearing capacity of printed elements. However, such shear-induced fiber alignment is highly sensitive to rheological properties. This study investigates how variations in dynamic yield stress (τd) and plastic viscosity (μ), influence the extrudability, fiber orientation and dispersion, and anisotropic mechanical behavior of ultra-high-performance concrete (UHPC). Five viscosity-modifying agent (VMA) types were incorporated at two content levels to modify the rheology of printable UHPC. Results showed that moderate VMA additions improved printability, whereas excessive contents markedly increased τd and μ; …

How Does Competitive Adsorption Between Vma And Pce Influence Yield Stress Of Cement Paste? A Novel Insight From Interparticle Forces And Percolation Threshold, Huamin Sun, Le Teng, Xiaohan Yu, Xin Shu, Zhangli Hu, Jiaping Liu, Kamal H. Khayat

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Viscosity modifying admixture (VMA) and polycarboxylate superplasticizer (PCE) are often combined to optimize rheological properties of cement-based materials. However, the competitive adsorption of these complex admixtures can greatly influence rheological properties. Many studies have investigated the variation of yield stress due to competitive adsorption between VMA and PCE; but the mechanisms are not fully understood. This study aims to shed a new light on this question in cement paste systems prepared with low water-to-binder ratios of 0.16–0.30. The competitive adsorption of VMA and PCE was quantitatively assessed using the Total Organic Carbon and Ultraviolet-Visible Spectroscopy measurements. The effect of competitive …

Transforming Dredged Sediment Into Reactive Clay: Critical Review Of Calcination, Reactivity, And Sustainable Valorization As Supplementary Cementitious Material, Seongho Han, Sanghwon Wi, Koochul Ji, Keun Hyeok Yang, Farshad Rajabipour, Kamal H. Khayat, Jinyoung Yoon

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Dredged sediment (DS) is generated worldwide in large volumes through routine port and waterway maintenance, yet its disposal presents environmental and economic challenges. Recently, calcined dredged sediment (CDS) has emerged as a supplementary cementitious material (SCM), offering a viable alternative to traditional SCMs, such as fly ash and slag cement. This review synthesizes current knowledge on the physical, chemical, and mineralogical characteristics of raw DS and pretreatment strategies aimed at dewatering, organic matter removal, and contaminant stabilization. The effects of calcination on the production of reactive amorphous aluminosilicates are also discussed. Emphasis is placed on physicochemical changes revealed by experimental …

Low-Carbon Concrete For Sustainable Construction: A Comprehensive Review Of Performance Characteristics, Implementation Challenges, And Decarbonization Pathways, Fazel Azarhomayun, Jingjie Wei, Kamal H. Khayat

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Reducing the carbon footprint of concrete has become a central objective in sustainable construction. Low-carbon concrete (LCC), developed primarily through clinker reduction, supplementary cementitious materials, and alternative binder strategies, offers a promising route for lowering embodied emissions while maintaining the performance requirements of structural concrete. This comprehensive review consolidates the current state of knowledge on LCC, identifies critical research and implementation gaps, and examines its material composition, mixture-design methodologies, performance characteristics, structural applications, implementation challenges, and decarbonization pathways. Single-SCM systems have been reported at clinker-replacement levels approaching 50%, although durability at these replacement levels, particularly carbonation resistance, remains system- and …

Recent Advances In The Rheological Properties Of Ultra-High-Performance Concrete: A Critical Review, Le Teng, Kamal H. Khayat, Jiaping Liu

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Ultra-high-performance concrete (UHPC) with adapted rheology continues to attract interest considering the requirement for novel processing techniques such as self-consolidating, pumping, spraying, and three-dimensional (3D) printing. The rheology of UHPC is complex due to its high solid volume fraction, low water content, and wide range of constituent materials that affect its flow properties. This work provides guidance for tailoring the mixture proportioning of UHPC to secure proper rheological properties and performance of UHPC for various applications. In the first part of this work, key physical, physicochemical, and chemical factors that can affect the rheological properties of UHPC are discussed. Rheological …

An Analytical Framework For Quantifying Urban And Community Resilience To Natural Hazards From Cell-Phone Gps-Location And Traffic-Flow Data, Georgios Chatzikyriakidis

Civil and Environmental Engineering Theses and Dissertations

Urban areas are increasingly exposed to natural hazards while accommodating a growing share of the global population, yet a consistent science-based framework for quantifying urban and community resilience remains lacking. This dissertation develops a physics-based analytical framework grounded in statistical mechanics and the quantitative theory of Brownian motion. A city is conceptualized as a complex medium in which citizens move analogously to Brownian particles within a viscoelastic environment, influenced by socioeconomic interactions and infrastructure functionality.

A central premise is that urban resilience, interpreted as engineering resilience (an outcome), can be quantified through a single metric: the mean-square displacement MSD=⟨r²(t)⟩, of …

Computer Vision And Machine Learning Approaches For Defect Detection In 3d-Printed Cementitious Materials: A Systematic Review, Muhammad Ali Musarat, Ruben Paul Borg, Jingjie Wei, Carl James Debono, Kamal Khayat

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

3D printing is evolving at a fast pace in both the manufacturing and construction sectors. These advancements can greatly benefit these industries. However, the 3D printing of concrete structures presents some challenges due to defects in the 3D concrete printed elements. Hence, this study systematically reviews Artificial Intelligence (AI)-driven techniques, such as Computer Vision and Machine Learning, to identify surface defects that can occur in 3D-printed cementitious material structures. The adopted methodology was the PRISMA statement with the aim of reporting the systematic review and meta-analysis. Two well-known databases, Web of Science and Scopus, were utilised for data extraction of …

Behavior Of A Mildly Skewed Network Tied-Arch Bridge During Construction And Early Service Life, Harsha Amunugama

Dissertations

This dissertation work investigated the structural performance of the 2nd Avenue Bridge in Detroit, Michigan, the first skewed, unbraced network tied-arch bridge in the U.S. The 245-ft long, 96.5-ft wide bridge features an 18-degree skew. The bridge was constructed using accelerated bridge construction (ABC) techniques, including off-site fabrication at a bridge staging area (BSA) and installation via self-propelled modular transporters (SPMTs) and lateral launching, enabling the completion of construction with minimal disruptions to I-94 traffic and improved safety.

Given the unique structural configuration of the bridge, the use of innovative construction techniques, and differences observed in structural responses predicted by …

Toward Sustainable 3d Printable Cementitious Materials: Low-Carbon Design With Fiber Reinforcement, Nima Mahmoudzadeh Vaziri

Miners Solving for Tomorrow Research Conference

3D printing of cementitious materials, as an emerging construction technology, faces challenges in both mechanical performance and sustainability. Conventional mixture designs rely on high cement contents, leading to increased CO2 emissions, while printed elements often exhibit brittle behavior with limited crack resistance and reduced post-cracking performance. This study investigates the development of low-carbon 3D printed cementitious composites using environmentally friendly supplementary cementitious materials (SCMs) and fillers, combined with fiber reinforcement to enhance mechanical performance. Locally available SCMs and fillers were incorporated to significantly reduce cement content (>40%) and improve sustainability. Fiber reinforcement was introduced to mitigate brittleness and enhance …

Iconic Henry Street Bridge In Indianapolis, Marshall Lachecki, Keith Echternach, Mary Appel

Purdue Road School

The iconic new Henry Street bridge over the White River in Indianapolis is a connection to the west side of downtown Indy.  From the challenging hydraulics requirements to the bridge concepts, design, procurement and through construction and archaeology work, the City has worked with many stakeholders and the public to make this new crossing a success.  This presentation will focus on design elements of the bridge while touching upon other project elements.

New Insights Into Dynamic Evolution Of Colloidal Network Structure During Early-Age Hardening Of Cementitious Materials, Hengrui Liu, Kaiyin Zhao, Shipeng Zhang, Hanghua Zhang, Shuangshuang Liu, Lucen Hao, Hongyan Ma, Kamal Khayat, Chi Sun Poon

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The evolution of microstructure in cementitious materials during their transition from fluid to solid state plays a critical role in determining their ultimate mechanical strength and overall performance. This hydration stage primarily involves a dynamic densification process occurring within the colloidal network. However, the field of cement-based materials currently lacks a comprehensive theoretical framework and associated parameters capable of effectively characterizing the specific structural regions within this network. In this study, we propose an Improved Particle Linkage (IPL) theory for describing the strength, types, and quantities of particle linkages within colloidal network. The IPL theory classifies the internal network structure …

Impact Of Femalized Kinesthetic Learning Model On African American Middle School Girls’ Career Interest, Mercy F. Fash, Andrea Ofori-Boadu

Journal of Global Education and Research

Engaging African American middle school girls in out-of-school-time (OST) Architecture, Engineering, and Construction (AEC) programs can boost interest in male-dominated AEC careers. This study adopts Lent’s Social Cognitive Career Theory to evaluate the impact of an OST feminized AEC kinesthetic learning model (fAEC-KLM) on the career interests of this demographic. Through a qualitative research approach, fourteen (14) African American middle school girls from Guilford County, NC, completed pre- and post-interviews on how fAEC-KLM interactions influenced their AEC career interests. Inductive thematic analysis was carried out on transcribed interviews. Results show that effective components, such as lectures on AEC, bridge construction …

Advances And Challenges In Nano-Modified Cementitious Composites: Mechanisms, Dispersion Strategies, And Impact On Mechanical Properties, Fatemeh Mohammadi Ghahsareh, Pengwei Guo, Nusrath Jaha, Yi Bao, Kamal H. Khayat, Weina Meng

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Nanomaterials are increasingly utilized to enhance the mechanical properties, durability, and functionality of concrete materials but face challenges such as agglomeration and uneven dispersion in cementitious systems, which can offset the intended improvements. This paper reviews the advances and challenges associated with nano-modified cementitious composites, elucidating fundamental mechanisms and highlighting strategies for overcoming the challenges through experimental and computing techniques. The reviewed contents include (1) the classification of nanomaterials commonly used in cementitious systems and the mechanisms through which they enhance the mechanical properties of cementitious composites; (2) challenges of nanomaterials such as agglomeration in water, re-agglomeration in cementitious systems, …

Enhancing Health And Safety Practices In Construction Site In Developing Nations Through Technology Advancement In South Western Nigeria, Mubaraq Lawal, Abba Mahmud, Ismail Gbolahan Dere, Thankgod Agbo Owoicho

CSID Journal of Infrastructure Development

The construction sector plays a critical role in urban development and economic growth, yet it continues to face major challenges that threaten worker health and safety. Traditional safety measures are not always sufficient for the complex conditions found on construction sites, which creates a need for technology‑based solutions. This study investigates the relationship between technology adoption and health and safety practices in the construction industry in Lagos, Nigeria. The study identifies the major causes of site accidents, examines the level of technology use on construction sites, and reviews existing literature through both primary and secondary data. Primary data were collected …

The Impact Of Relative Bridge Width On Highway Crashes In Nebraska, Mujahid Ali Bahadur

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

This research examines how bridge width relative to the approach roadway affects crash occurrence on Nebraska highways. The Nebraska Department of Transportation-(NDOT) Bridge Design Manual sets minimum bridge widths based on roadway classification, traffic projections, and the American Association of State Highway and Transportation Officials’ (AASHTO) Load and Resistance Factor Design (LRFD) criteria. While these guidelines ensure structural and functional adequacy, they do not incorporate safety performance analyses based on crash data. This leaves an important gap in understanding how bridge and approach roadway width decisions influence safety outcomes.

This research has four objectives: (1) evaluate crash frequency across different …

Co2-Induced Changes In Rheology, Structural Evolution, And Particle Characteristics Of Cement Paste, Seongho Han, Tae Yong Shin, Seung Mo Kim, Jae Hong Kim, Kamal H. Khayat

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The injection of carbon dioxide (CO₂) into cementitious systems has emerged as a promising approach to enhancing sustainability in concrete production. This study explores the impact of CO₂ injection on the rheological behavior, structural build-up, and particle size evolution of cement paste by systematically varying the water-to-cement ratio (w/c) (0.35, 0.4, and 0.5) and CO₂ concentration (0.06, 0.28, and 0.84 mol). Rheological analysis revealed a significant increase in initial yield stress with CO₂ injection. Using the Modified Bingham model, yield stress increased by 72 % and 150 % for 0.28- and 0.84-mol CO₂, …

Influence Of Mixing Duration And Absorption Characteristics Of Superabsorbent Polymers On The Fresh And Hardened Properties Of High-Performance Concrete, Yu Cun Gu, Kamal H. Khayat

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This study investigates the combined influence of superabsorbent polymers (SAPs) with distinct absorption kinetics and extended mixing sequences on the rheological, mechanical, and transport properties of high-performance concrete (HPC). Two SAPs—an ionic acrylamide-co-acrylic acid copolymer (SAP-P) and a non-ionic acrylamide polymer (SAP-B)—were incorporated at an internal curing level of 100%. The impact of extended mixing times (3, 5, and 7 min) following SAP addition was systematically evaluated. Results showed that longer mixing durations led to increased superplasticizer demand and higher plastic viscosity due to continued water absorption by SAPs. However, yield stress remained relatively stable owing to the dispersing effect …

Treatment And Activation Effects On Kaolinite-Based Earth Concrete, Mojtaba Kohandelnia, Maroua Zerzouri, Ammar Yahia, Kamal H. Khayat

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Self-consolidating earth concrete (SCEC) addresses the long construction process of conventional earthen constructions and their structural limitations, while further efforts are needed to enhance its sustainability. This study explores the development of a kaolinite-based self-consolidating earth paste (SCEP) due to their blended powder system, incorporating raw and treated (calcined and ground-calcined) kaolinite under various activation techniques, such as water hydration, sodium hexametaphosphate (NaHMP), and sodium hydroxide (NaOH) activation. The synergistic effect of calcination and mechanosynthesis on rheological, mechanical, structural, and microstructural properties of SCEP were investigated. Mechanically treated kaolinite increased yield stress, plastic viscosity, storage modulus evolution, and build-up index, …

Hickory Street Square Revitalization, Spencer Knight, Grace Dungan, Tim Kula, Evan Lauritsen, Lindsey Mennenga

Honors Program: Senior Projects (Public)

The Hickory Street Square Revitalization Project seeks to transform a central public space in Sidney, Nebraska into a dynamic, community-oriented area that supports local events, economic activity, and cultural heritage. The project addresses six core objectives: 1) convertible street design, 2) parking lot reconfiguration, 3) public amenities, 4) event flexibility, 5) lighting and signage, and 6) old electric plant renovation. A conceptual design was developed by the design team (S.T.E.E.L. Sentinel Solutions) by synthesizing the most effective features of three preliminary alternatives, shaped further through community feedback and evolving project constraints. The final project design minimizes disruption to existing activity …

Development Of Timber Bridge Railing And Approach Guardrail Transition, Aaron Lechtenberger

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

Timber bridges with transverse and longitudinal bridge decks are increasingly utilized across the United States. However, limited research exists to develop bridge railing systems for high-service-level roadways that meet current vehicular impact safety standards. In response to this gap, the United States Department of Agriculture - Forest Service -Forest Products Laboratory (USDA-FS-FPL), in collaboration with the Midwest Roadside Safety Facility (MwRSF), initiated a research program to develop, crash test, and evaluate higher-service-level bridge railings and approach guardrail transitions (AGTs) compliant with the American Association of State Highway and Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH).

This study continued …

Comparative Analysis On Design Error Risks In Design-Bid-Build And Design-Build Construction Approaches, Eradius Edward Rwakarehe

Tanzania Journal of Engineering and Technology (TJET)

This study was conducted to compare design errors risk in Design-Bid-Build (DBB) (traditional) and Design-Build (DB) methods in building projects. Several construction projects under both DB and DBB method were reviewed. On most of construction projects under DB method, it was found that there were over supply of floor area due to different reasons. Also, it was found that, clients’ requirements were changed during project execution, which resulted into change on schedule, contract value and project quality. It was also revealed that in most cases, designs were in accordance with the clients’ requirements as submitted earlier but during construction clients …

Digital Fabrication With Fiber-Reinforced Concrete, Haodao Li, Kamal H. Khayat

Miners Solving for Tomorrow Research Conference

No abstract provided.

Underlying Mechanisms Of The Effect Of Microfines Of Manufactured Sand On Non-Linear Structural Build-Up Of Cement Paste, Jiang Zhu, Jiaping Liu, Kamal H. Khayat, Xin Cheng, Wei Zhao, Zhen Li, Xin Shu, Yongbo Huang

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The rheological properties of cement-based materials made with manufactured sand vary with the content and physio-chemical properties of microfines in the sand. However, the evaluation of rheological properties regarding the structural build-up at early-age hydration remains challenging for the cementitious materials prepared with different manufactured sands, due to complicated underlying structuration mechanisms. This paper studies the effect of disparate microfines of different manufactured sands on the non-linear growth of static yield stress of cement pastes at rest. The paste mixtures were prepared with 0.40 and 0.275 water-to-cement mass ratio (W/C) and had a fixed mini-slump flow of 240 ± 5 …

Bell Ford Bridge Reconstruction Project, Daniel Kurdziel, Jim Barker, Matt Lee

Purdue Road School

The Bell Ford Bridge was originally constructed in 1869 until it collapsed in the 20th century. The remains were salvaged and stored for 20 years until it was to be rebuilt in Hamilton County, IN. This is the only remaining Combination Post Truss in existence and was rebuilt using 95% of the original iron and 10% of the original timber.

Effect Of Shrinkage-Mitigating Materials, Fiber Type, And Repair Thickness On Flexural Behavior Of Beams Repaired With Fiber-Reinforced Self-Consolidating Concrete, Jingjie Wei, Kamal H. Khayat

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

While self-consolidating concrete (SCC) has emerged as a highly effective approach for the repair of concrete structures, there have been few investigations regarding the effect of the combination of different fiber and shrinkage-mitigating material types (shrinkage-reducing admixture, SRA; superabsorbent polymer, SAP; and expansive agent, EA) on the flexural behavior of repaired structures. This study aims to explore the influence of three different shrinkage-mitigating materials (1.25%–2.5 % SRA, 4%–8% EA, and 0.2%–0.4 % SAP), four fiber types (two macro synthetic fibers, MSFA and MSFB; 5D hooked steel fibers, 5D; a combination of 80 % 3D hooked steel +20 % short steel …

Flexural Post-Cracking Performance Of Macro Synthetic Fiber Reinforced Super Workable Concrete Influenced By Shrinkage-Reducing Admixture, Jingjie Wei, Nima Farzadnia, Kamal H. Khayat

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Most literature has focused on the effect of shrinkage-reducing admixture (SRA) in shrinkage mitigation resistance of concrete. This study aims to examine the impact of SRA on the efficiency of macro synthetic fibers (MSF) in enhancing the flexural post-cracking behavior of fiber-reinforced super workable concrete (FR-SWC). A comparative analysis of the influence of fiber combinations on the flexural post-cracking behavior of beams is also included. Results showed that a higher dosage of SRA, particularly at 5 % by mass of binder, had a noticeable negative impact on flexural post-cracking performance of beams while exhibiting positive effect on workability and shrinkage …

Accelerated Test Method (Atm) For The Evaluation Of External Sulfate And Chloride Attack On Concrete Using Artificial Climate Environment (Ace): An Assessment Of Methodology, Eli Walker

College of Graduate Studies: Theses & Dissertations

This study seeks to investigate a testing methodology that utilizes accelerated testing methods (ATM) in conjunction with nondestructive testing methods (NDT) to assess destructive ion attacks on concrete. Through the testing of concrete samples, the impacts of chloride and sulfate ions on concrete will be tested by subjecting concrete to cyclic testing in an artificial climate environment. Electrical resistivity (ER) and ultrasonic pulse velocity (UPV) testing will evaluate the impact of the accelerated testing on the migration of destructive ions within the pore structure of the tested concrete. Based on this investigation, comparisons between accelerated, non-accelerated, and control samples will …

Influence Of Deck Area And Average Daily Traffic On The Deterioration Of Bridge Superstructures., Faysal Ahamed

Graduate Theses, Dissertations, and Problem Reports (ETD)

State Departments of Transportation (DOTs) are responsible for maintaining approximately 623,000 bridges across the United States. Effective bridge management requires a comprehensive understanding of the factors influencing structural deterioration. Numerous studies have explored the effects of average daily traffic (ADT) and deck area (DA) on bridge deck deterioration. Given the interdependence between bridge decks and superstructures, it is plausible that ADT and DA significantly influence superstructure condition ratings and deterioration trends. However, their impact on superstructures remains insufficiently studied. In addition, existing studies primarily focus on overall bridge deterioration without adequately differentiating between superstructure designs and materials and maintenance authorities. …

Comparative Analysis Of Lidar And Close-Range Photogrammetry Techniques For Inspection Of Mse Walls In Two Georgia Bridges, Md. Mehrab Hossain

College of Graduate Studies: Theses & Dissertations

Mechanically Stabilized Earth (MSE) retaining walls are durable, settlement tolerant, easy to install, and present cost-effectiveness, in highway bridges. Nevertheless, the cost of repairing MSE walls is high, and it is crucial to have an accurate, quantitative, and scalable inspection method for early detection of potential problems. This study aims to analyze and evaluate undesired displacements that may affect these walls over time. For this, two remote-sensing technologies are considered: Light Detection and Ranging (LiDAR) and 3D Close Range Photogrammetry (CRP). Their performances are compared against an accurate Robotic Total Station (RTS) device, serving as the benchmarking instrument. This work …

The Impact Of Skew On The Flexural Behavior Of Press-Brake-Formed Tub Girders, Matthew Allan Weatherholt

Graduate Theses, Dissertations, and Problem Reports (ETD)

The Short Span Steel Bridge Alliance (SSSBA) is a group of bridge and buried soil steel structure industry leaders who have joined together to provide educational information on the design and construction of short span steel bridges in installations up to 140 feet in length. Press-brake-formed-tub-girders (PBFTGs) were developed by a technical working group within the SSSBA in response to a rising demand for rapid infrastructure replacements for short span bridge applications. PBFTGs are produced from structural steel plate and can be finished as weathering steel or galvanized. After being cold bent to the appropriate shape, shear studs are welded …