Macro - And Microstructure Evaluation And Field Applications Of Concrete With Recycled Glass Pozzolan,
2020
CUNY City College
Macro - And Microstructure Evaluation And Field Applications Of Concrete With Recycled Glass Pozzolan, Marija Krstic
Dissertations and Theses
Concrete is the most used material in the world, second only to water. Conventional concrete is produced with Portland cement (PC). The production of cement is an energy intensive operation that has raised significant environmental concerns, since one ton of cement generates an equal ton of CO2. In the USA about 90 million tons of cement are used annually, with 3 million tons used in New York. Most contemporary concrete applications for buildings and infrastructure use high-performance concrete (HPC) mixtures which are produced by replacing a percentage of cement with supplementary cementitious materials (SCMs), consisting mainly of fly-ash …
Redox-Active Porous Organic Materials For Electrochemical Energy Storage Applications,
2020
Virginia Commonwealth University
Redox-Active Porous Organic Materials For Electrochemical Energy Storage Applications, K. Shamara Weeraratne
Theses and Dissertations
As the demand for renewable energy technologies grows, so does the need for cheaper, more efficient rechargeable batteries to store the energy. While lithium-ion battery (LIBs) technology is well established, it suffers from limited lithium supplies. Furthermore, the highly toxic transition metals used in the electrodes places a huge burden on the environment. Therefore, replacing lithium with more economical sodium metal in rechargeable batteries (i.e. sodium-ion batteries, SIBs) has garnered considerable attention. Despite the fact that sodium and lithium share similar electrochemical properties, which may cause the transition from lithium to sodium easier, the larger ionic radius of Na+ …
Time-Dependent Reliability Framework For Durability Design Of Frp Composites,
2020
West Virginia University
Time-Dependent Reliability Framework For Durability Design Of Frp Composites, Rajneesh Kumar Bharil
Graduate Theses, Dissertations, and Problem Reports (ETD)
The life-cycle performance, durability, and aging characteristics of Fiber Reinforced Polymer (FRP or Structural Composites) have been of keen interest to the engineers engaged in the FRP design, construction, and manufacturing. Unlike conventional construction materials such as steel and concrete, the design guidelines to account for the aging of FRP are somewhat scattered or not available in an approved or consistent format. Loss of strength over time or aging of any structural material should be of concern to engineers as the in-service lifespan of many engineering structures is expected to exceed 100 years. Use of durability strength-reduction factors or factors …
Ultrasonic-Based Condition Assessment Of Wooden Utility Poles,
2020
University of Denver
Ultrasonic-Based Condition Assessment Of Wooden Utility Poles, Yishi Lee
Electronic Theses and Dissertations
More than 300 million utility poles shoulder the utility grid in the United States. However, the ineffectiveness of the current inspection process causes roughly a third of utility poles removed from the service deemed suitable for reuse. Due to the utterly essential role of the power infrastructure, budget shrinkage, and the structural degradation of the modern distribution grid, this Ph.D. dissertation addresses the challenges by proposing a physics-based signal analysis method with a jointly developed ultrasonic UB1000 system c to enhance the objectivity in ultrasonic-based nondestructive evaluation (NDE). The proposed methodology has been deployed commercially in the field and featured …
Buckling Load Study On Pop Nut (Rivet) Using Finite Element Analysis,
2020
Michigan Technological University
Buckling Load Study On Pop Nut (Rivet) Using Finite Element Analysis, Saurabh Shankar Shegokar
Dissertations, Master's Theses and Master's Reports
This study highlights the material behavior in riveting operation that includes buckling load analysis using ABAQUS. Finite Element Analysis is used to find the buckling load vs. Displacement results and validated with the results obtained in physical testing of rivet (POP Nut). A mesh sensitivity study is performed using ABAQUS to understand the optimum mesh size for this analysis. An axisymmetric model with contact properties is created and simulated to reduce the simulation time using ABAQUS. The results obtained through Finite Element Analysis show a good resemblance with the testing results. Design changes were suggested to achieve better results that …
Influence Of Rapid Solidification And Wrought Processing On Precipitation Strengthening And Deformation Mechanisms In Al-Sc-Zr Alloys,
2020
Michigan Technological University
Influence Of Rapid Solidification And Wrought Processing On Precipitation Strengthening And Deformation Mechanisms In Al-Sc-Zr Alloys, Yang Yang
Dissertations, Master's Theses and Master's Reports
Al-Sc-Zr alloys have drawn increasing attention in the last several decades due to their strengthening and coarsening resistance. In this study, solute concentrations of Sc and Zr were increased beyond their equilibrium solubilities without primary precipitate formation using melt-spinning. The melt-spun ribbon was metallurgically bonded into bulk shape using extrusion. With the proper aging treatment, the mechanical properties of the supersaturated melt-spun ribbon and extruded rod were found to be significantly higher than a baseline dilute alloy. Increased mechanical properties include microhardness, tensile strength at ambient-temperature, and compressive strength and threshold stress at and elevated-temperature. These increases were related to …
Increasing Access To Pv Technology Through Sustainable Racking: A Review Of Existing Literature And Ground Mounted Fixed Tilt Designs, And What Can Be Done Next,
2020
Michigan Technological University
Increasing Access To Pv Technology Through Sustainable Racking: A Review Of Existing Literature And Ground Mounted Fixed Tilt Designs, And What Can Be Done Next, Parijata Prabhakara
Dissertations, Master's Theses and Master's Reports
There is a lack of literature on the structural balance of systems (BOS), also called racking, for ground mount, fixed-tilt solar PV systems. Literature that exists discusses mostly rooftop racking and installations, additional wind loading, and weight considerations imposed on roofs, and little guidance is provided in building codes. The lack of peer-reviewed guidance on design requirements for domestic and large-scale application solar PV racking systems leaves most consumers relying on expensive, patented, off-the-shelf hardware. As PV cell technology and module costs have improved, we can start to focus on PV BOS improvements (particularly racking) and move towards sustainable designs …
Investigation On The Mechanical Properties And Microstructure Analysis Of Micro-Resistance Spot Welding Between Stainless Steel 316l And Tl-6al-4v,
2020
Universiti Malaya
Investigation On The Mechanical Properties And Microstructure Analysis Of Micro-Resistance Spot Welding Between Stainless Steel 316l And Tl-6al-4v, Mohd Mansor Muhammad Safwan
Student Works (2020-2029)
In this study, ASS 316L and Ti-6Al-4V were welded together by micro-resistance spot welding (μRSW) at different combinations of welding parameters using specifically design electrode geometry in order to acquire the optimal combination of welding parameters. The welded joint were subjected to tensile shear strength test to determine the influence of welding current, welding time, welding force and different design of elctrode tip on the mechanical properties and the strength of the welded joint. The experiment was conducted by using full factorial design of experiment (DoE) with L27 orthogonal array and utilizing the analysis of variance (ANOVA) to obtain the …
Retrofit Of Corroded Corrugated Metal Culverts Using Gfrp Slip-Liner,
2019
University of New Mexico
Retrofit Of Corroded Corrugated Metal Culverts Using Gfrp Slip-Liner, Rahulreddy Chennareddy
Civil Engineering ETDs
Culverts are water conveyance structures, typically used to allow water flow and maintain a balance between the flow streams without interrupting structures such as highways and bridges. Corrugated metal pipes (CMPs) have been used as culverts in North America since the 1950s because of their low cost and simple construction method. Today, the corrosion of CMPs is a major problem faced by all U.S. Departments of Transportation. There is an urgent need to provide an efficient solution, one that is corrosion-resistant, to retrofit thousands of corroded CMPs across the country. High specific strength, high strength to weight ratio, corrosion resistance, …
Effect Of Incorporating Pottery And Bottom Ash As Partial Replacement Of Cement,
2019
The Islamic University of Gaza
Effect Of Incorporating Pottery And Bottom Ash As Partial Replacement Of Cement, Bassam A. Tayeh, Doha M. Alsaffar, Lawend K. Askar, Asmahan Issa Jubeh
Karbala International Journal of Modern Science
This study addressed the environmental constraints in cement production. Ordinary Portland cement (OPC) was replaced with pottery powder (PP, produced by grinding locally available pottery) and bottom ash (BA) at 10%, 20% and 30% of cement mass. Moreover, 4% calcium chloride solution (CaCl2.2H2O) was used as mixing water. Material properties, such as standard consistency, setting time and compressive strength, were measured with different percentages of OPC replacement with PP and BA. Results indicated that the replacement with PP and BA increased the water demand to achieve the standard consistency. These results revealed that the strength evolution …
Development Of A Mix Design Adjustment Method For Fiber Reinforced Concrete And Super High Performance Concrete Based On Excess Paste,
2019
University of Nebraska-Lincoln
Development Of A Mix Design Adjustment Method For Fiber Reinforced Concrete And Super High Performance Concrete Based On Excess Paste, Joe Malloy
Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research
The main objective of this study was to develop a mix design adjustment method for Fiber Reinforced Concrete (FRC) that would maintain appropriate workability while improving hardened concrete performance. A literature review was conducted to examine existing methods for adjusting mix designs to account for fiber introduction. It was found that while increasing fine aggregate and cement paste content can make up for lost workability with the addition of fibers, no rational mix design adjustment method is available. Reference mix designs from the Nevada Department of Transportation and the Nebraska Department of Transportation were used, and this study focused on …
Ultrasonic Wave Propagation In Copper/Graphene Metal Matrix Composites,
2019
University of Arkansas, Fayetteville
Ultrasonic Wave Propagation In Copper/Graphene Metal Matrix Composites, Casey Lindbloom
Mechanical Engineering Undergraduate Honors Theses
Emerging metallic composite materials implanted with graphene sheets are showing immense promise, with benefits being observed with regards to mechanical, thermal, and electrical material properties. This research aims to investigate the effects on ultrasonic wave propagation in Copper/Graphene Metal Matrix Composites (Cu/Gr MMCs) with varying graphene arrangements inspired from nacre and bone nanoscale material distributions. To accomplish this, the molecular dynamics (MD) method is utilized to simulate nanoscale wave propagation on a set of Cu/Gr MMCs with differing graphene arrangements and volume percentages ranging up to 4.56%. The computational model results are then analyzed to determine the variation in energy …
Mandela Splash Pad Pre-Construction Plan,
2019
University of Nebraska at Omaha
Mandela Splash Pad Pre-Construction Plan, Levi Sandbulte
Theses/Capstones/Creative Projects
In the construction industry, it is the responsibility of the general contractor to take the architect’s ideas and turn it into a real building. Many times this requires ample communication and several drafts. This efficient execution of this process is vital to the completion of a successful project. In this project, I practice this communication process. The challenge presented by the owner is to build an affordable splash pad, and without impacting the construction schedule of the Early Childhood Development Center (ECDC) that is being built on the same property at the same time. This proposal gives the owner a …
Additively Manufactured Continuous Carbon Fiber Thermoplastic Composites For High-Performance Applications,
2019
University of New Mexico
Additively Manufactured Continuous Carbon Fiber Thermoplastic Composites For High-Performance Applications, Nekoda Van De Werken
Mechanical Engineering ETDs
The goal of this dissertation is to provide a foundation for the advancement of additive manufacturing (AM) toward production of high-performance carbon fiber reinforced polymer matrix composites (CFRPs). AM can provide valuable advantages over conventional composite manufacturing techniques, including the control over fiber orientation, capability of manufacturing complex geometries, out-of-autoclave processing, elimination of the need for composite tooling, and the ability to perform lights-out manufacturing. Currently, however, a suite of challenges related to modelling, design, manufacturing defects, and general limitations in the current understanding of the processing-structure-property relationships exist in AM of composites. To this end, this dissertation investigates novel …
The Application Of Gray-Scale Level-Set Method In Segmentation Of Concrete Deck Delamination Using Infrared Images,
2019
University of Nebraska-Lincoln
The Application Of Gray-Scale Level-Set Method In Segmentation Of Concrete Deck Delamination Using Infrared Images, Chongsheng Cheng, Zhigang Shen
Department of Construction Engineering and Management: Faculty Publications
Conventional nondestructive delamination detection of concrete pavements through thermography is often based on temperature contrasts between delaminated and sound areas. Non-uniform backgrounds caused by the environmental conditions are often challenging for contrast-based methods to robustly differentiate the delaminated areas from the sound areas. Instead of focusing on the temperature contrast, this study proposes a temperature gradient-based level set method (LSM) to detect boundaries for delamination segmentations. A modified edge indicator function is developed to represent the normalized temperature gradient of a thermal image. The experimental study was conducted to evaluate its applicability and stability for boundary detection in terms of …
Micro-Mechanical Analysis Of Corrosion Products Formed During Long-Term Carbonation Induced Corrosion Of Steel,
2019
Faculty of Civil Engineering, University of Zagreb
Micro-Mechanical Analysis Of Corrosion Products Formed During Long-Term Carbonation Induced Corrosion Of Steel, Marijana Serdar, Dubravka Bjegovic, Valérie L’Hostis, Stéphane Poyet, Damien Féron
International Conference on Durability of Concrete Structures
During corrosion distinct types of corrosion products form, composed of different ratios of ferrous ions and oxide, hydroxides. Corrosion products have different physical and mechanical properties, mainly density, resistivity, volume and modulus of elasticity compared to iron. Knowing properties of corrosion products is indispensable for service life modelling of structures and can give valuable insight into the long-term corrosion propagation process. In this study micro-indentation method was used to evaluate mechanical properties of different layers formed during long-term carbonation induced corrosion of steel in concrete. Investigation was performed on three sets of reinforced concrete samples, that underwent corrosion during 50, …
Development Of Engineered Cementitious Composites With Conductive Inclusions For Use In Self-Sensing Applications,
2019
Heriot-Watt University
Development Of Engineered Cementitious Composites With Conductive Inclusions For Use In Self-Sensing Applications, Benny Suryanto Dr, Danah Saraireh Ms, Steven Walls Mr, Jaehwan Kim Dr, W John Mccarter Prof
International Conference on Durability of Concrete Structures
The mechanical and a.c. electrical properties of a new varietal of engineered cementitious composite (ECC) incorporating conductive inclusions are presented. Electrical measurements were undertaken over a wide frequency range while curing and when under uniaxial tensile loading to study the influence of ongoing hydration and multiple microcrack formation on the composite electrical impedance. When presented in Nyquist format, the work shows that conductive inclusions reduce the bulk resistance of the composite while enhancing its polarizability, transforming the classic, single-arc bulk response of typical cement-based materials to a two-arc response. The bulk resistance was shown to increase with time and damage, …
Why The Crackling Deformations Of Single Crystals, Metallic Glasses, Rock, Granular Materials, And The Earth’S Crust Are So Surprisingly Similar,
2019
University of Illinois at Urbana-Champaign
Why The Crackling Deformations Of Single Crystals, Metallic Glasses, Rock, Granular Materials, And The Earth’S Crust Are So Surprisingly Similar, Karin A. Dahmen, Jonathan T. Uhl, Wendelin J. Wright
Faculty Journal Articles
Recent experiments show that the deformation properties of a wide range of solid materials are surprisingly similar. When slowly pushed, they deform via intermittent slips, similar to earthquakes. The statistics of these slips agree across vastly different structures and scales. A simple analytical model explains why this is the case. The model also predicts which statistical quantities are independent of the microscopic details (i.e., they are "universal"), and which ones are not. The model provides physical intuition for the deformation mechanism and new ways to organize experimental data. It also shows how to transfer results from one scale to another. …
Experimental And Numerical Investigation On The Irregularity Of Carbonation Depth Of Concrete Under Supercritical Condition,
2019
Wuhan University
Experimental And Numerical Investigation On The Irregularity Of Carbonation Depth Of Concrete Under Supercritical Condition, Hao Bao Masc, Min Yu Dr., Jianqiao Ye Dr., Lihua Xu Dr., Yin Chi Dr., J Ye
International Conference on Durability of Concrete Structures
The heterogeneity of a cement-based material results in a random spatial distribution of carbonation depth, which may significantly affect the mechanical properties and durability of the material. Currently, there is a lack of both experimental and numerical investigations aiming at a statistical understanding of this important phenomenon. This paper presents both experimental and numerical supercritical carbonation test results of concrete blocks. The random fields of porosity and two-dimension random aggregate model of concrete were proposed for the simulation. The carbonation depths are measured and distributed along the carbonation boundary by the proposed rapid image processing technique, which are then statistically …
Guiding Principles In Developing The South African Approach To Durability Index Testing Of Concrete,
2019
School of Civil & Environmental Engineering, University of the Witwatersrand, Johannesburg, South Africa
Guiding Principles In Developing The South African Approach To Durability Index Testing Of Concrete, Yunus Ballim, Mark Alexander
International Conference on Durability of Concrete Structures
Focused thinking on the possibility of early-age testing of concrete for long-term durability started in earnest during the late 1980’s in South Africa. Through sustained research, development and trial implementation on construction projects, three durability index (DI) tests have emerged, two of which have been adopted as national standard test methods for concrete construction, the remaining one being prepared a national standard. In this paper we review the guiding or foundational principles that directed the development of these DI tests, with a view to assessing the appropriateness and relevance of these guiding principles to modern concretes. The last 30 years …
