Structural Materials Commons^™

Evaluating A New Cem Iii/A Cement For Concretes Exposed To Harsh Acid Rich Environments, David Thompson, Niall Holmes, John Reddy

Conference papers

The Irish Annex to the European specification, performance, production and conformity of concrete, IS EN 206, recommends CEM III/B cement for acid rich environments containing between 66 to 80% GGBS. However, BS 8500, the UK annex to EN 206 and the British Research Establishment (BRE) Special Digest 1, recommends CEM III/A cement with a GGBS range of 36-65%. This project investigated the performance of a new CEM III/A cement produced by Ecocem Ireland in concretes exposed to such environments using an extensive suite of laboratory tests.

In Ireland, up to €5.8bn will be invested to provide fresh drinking water and …

A Parametric Study Of Meso-Scale Patterns For Auxetic Mechanical Behavior Optimization, Matthew C. Schuler

Honors Undergraduate Theses

This thesis focuses on the development, parameterization and optimization of a novel meso-scale pattern used to induce auxetic behavior, i.e., negative Poisson's ratio, at the bulk scale. Currently, the majority of auxetic structures are too porous to be utilized in conventional load-bearing applications. For others, manufacturing methods have yet to realize the meso-scale pattern. Consequently, new auxetic structures must be developed in order to confer superior thermo-mechanical responses to structures at high temperature. Additionally, patterns that take into account manufacturing limitations, while maintaining the properties characteristically attached to negative Poisson's Ratio materials, are ideal in order to utilize the potential …

Underwater Explosion Energy Dissipation Near Waterborne Infrastructure, Paul R. Smith

Theses and Dissertations--Civil Engineering

Underwater explosions pose a significant threat to waterborne infrastructure though destructive pressure waves that can travel significant distances through the water. However, the use of bubble screens can attenuate the peak pressure and energy flux created by explosions to safe levels. This study investigates the prediction of pressure wave characteristics based on accumulated data, the damage potential of underwater explosions based on applied loads and effective material strength, and the bubble screen parameters required to prevent damage. The results were compiled to form a procedure for the design and implementation of a bubble screen the protection of waterborne infrastructure.

Preliminary Investigation Into The Rate Of Carbonation Of Concrete Blocks Under Normal Production Yard Conditions, Aimee Byrne, Eanna Nolan

Conference papers

The release of CO2 from calcination during the manufacture of cement can be partially or fully offset by the CO2 it naturally absorbs during its lifetime. This paper reports results from a preliminary investigation into the rate of carbonation in concrete blocks stacked in a production yard over a period of 6 months. The blocks were stacked in a normal manner under natural exposure conditions. Carbonation progress was determined by splitting the blocks and spraying the freshly exposed surface with a phenolphthalein solution at intervals over the test period. It was found that the rate of the carbonation front progression …

Performance Of Masonry Blocks Containing Different Proportions Of Incinator Bottom Ash, Niall Holmes, Hugh O'Malley, Paul Cribbin, Henry Mullen, Garrett Keane

Articles

No abstract provided.

Characterization Of Dispersion And Residual Stress In Nanoparticle Reinforced Hybrid Carbon Fiber Composites, Alex Selimov

Honors Undergraduate Theses

Hybrid carbon fiber reinforced composites are a new breed of materials that are currently being explored and characterized for next generation aerospace applications. Through the introduction of secondary reinforcements, such as alumina nanoparticles, hybrid properties including improved mechanical properties and stress sensing capabilities can be achieved. In order to maximize these properties, it is necessary to achieve a homogeneous dispersion of particulate filler. Utilizing the photoluminescent properties of alumina, it is possible to compare local levels of particle concentration through emission intensities as a way to determine the effectiveness of the tested manufacturing parameters in increasing material homogeneity. Parameters of …

Methodology For Analyzing Epoxy-Cnt Phononic Crystals For Wave Attenuation And Guiding, Madhu Kolati

Dissertations, Master's Theses and Master's Reports

Phononic crystals (PhnCs) control, direct and manipulate sound waves to achieve wave guiding and attenuation. This dissertation presents methodology for analyzing nanotube materials based phononic crystals to achieve control over sound, vibration and stress mitigation. Much of the analytical work presented is in identifying frequency band gaps in which sound or vibration cannot propagate through these PhnCs. Wave attenuation and mitigation analysis is demonstrated using finite element simulation. Engineering principles from current research areas of solid mechanics, solid-state physics, elasto-dynamics, mechanical vibrations and acoustics are employed for the methodology. A considerable effort is put to show that these PhnCs can …

Heterogeneous Thermal Effects On Structural-Grade Steel, Eric Wickersham

Williams Honors College, Honors Research Projects

The AISC Steel Construction Manual covers structural steel design while at atmospheric and elevated temperatures. The manual does not, though, cover what happens to the steel after it has cooled from elevated temperatures. To fill in this knowledge gap, A36 steel was studied with respect to three main criteria: time, temperature, and cooling. Time was sub-divided into a standard burn (17-20min) and a prolonged burn (90min). Temperature was sub-divided into an average burn (600-800⁰F) and an extreme burn (>1200⁰F). To reach such temperatures, a forge was constructed and used during the burning process. Cooling was sub-divided into standard (air …

Design For Fractal Grid Generated Turbulence, Moira Gion

Maseeh Summer Undergraduate Research Experience

Fractal geometry can be used to find organization or order in something that appears to be in disorder, or chaos. Turbulence is viewed as one place where fractal geometry can be found in nature. The irregularity in fluid flow is dependent on the initial conditions. In the past, the idea of self-similarity has been used to develop statistical theories of energy cascade in a turbulent flow. Recent studies have done experiments on obstructing flows with fractal objects to observe intermittency, (or self-similarity) within a turbulent flow. Experiments on fractal grid generated turbulence has been performed by other research groups, so …

Corn Stover Biochar In Gypsum Board: Empirical Analysis Of Thermal Conductivity And Flexural Strength, Albena Yordanova

Dissertations and Theses @ UNI

Gypsum board, an economical and durable finish material for wall and ceiling construction in the United States and worldwide, is the component with the lowest thermal performance in a typical exterior wall assembly. It also constitutes a substantial portion of construction waste in landfills, potentially creating harmful environmental effects and dangerous gases. To minimize the negative effects of fast growing construction waste of gypsum in landfills and meet higher standards for energy efficiency in construction, there is a need to explore sustainable ways of improving thermal properties of gypsum board and recycling the material. Gypsum can be recycled and used …

Beyond Conventional C-Plane Gan-Based Light Emitting Diodes: A Systematic Exploration Of Leds On Semi-Polar Orientations, Morteza Monavarian

Theses and Dissertations

Despite enormous efforts and investments, the efficiency of InGaN-based green and yellow-green light emitters remains relatively low, and that limits progress in developing full color display, laser diodes, and bright light sources for general lighting. The low efficiency of light emitting devices in the green-to-yellow spectral range, also known as the “Green Gap”, is considered a global concern in the LED industry. The polar c-plane orientation of GaN, which is the mainstay in the LED industry, suffers from polarization-induced separation of electrons and hole wavefunctions (also known as the “quantum confined Stark effect”) and low indium incorporation efficiency that …

Improving The Capacity, Durability And Stability Of Lithium-Ion Batteries By Interphase Engineering, Qinglin Zhang

Theses and Dissertations--Chemical and Materials Engineering

This dissertation is focus on the study of solid-electrolyte interphases (SEIs) on advanced lithium ion battery (LIB) anodes. The purposes of this dissertation are to a) develop a methodology to study the properties of SEIs; and b) provide guidelines for designing engineered SEIs. The general knowledge gained through this research will be beneficial for the entire battery research community.

Three-Dimensional Microstructural Effects On Multi-Site Fatigue Crack Nucleation Behaviors Of High Strength Aluminum Alloys, Yan Jin

Theses and Dissertations--Chemical and Materials Engineering

An experimental method was further developed to quantify the anisotropy of multi-site fatigue crack initiation behaviors in high strength Al alloys by four-point bend fatigue testing under stress control. In this method, fatigue crack initiation sites (fatigue weak-links, FWLs) were measured on the sample surface at different cyclic stress levels. The FWL density in an alloy could be best described using a three-parameter Weibull function of stress, though other types of sigmoidal functions might also be used to quantify the relationship between FWL density and stress. The strength distribution of the FWLs was derived from the Weibull function determined by …

An Overview Of The Development Of Cement-Based Batteries For The Cathodic Protection Of Embedded Steel In Concrete, Aimee Byrne, Niall Holmes, Brian Norton

Conference papers

This paper presents an overview of the cement-based batteries developed in DIT for use in the cathodic protection of embedded steel in reinforced concrete undergoing chloride-induced corrosion. Cathodic protection delivers an external current (approximately 20mA per m2 of embedded steel) which effectively polarises the internal current generated during corrosion. The batteries developed in DIT comprise of a cement-based electrolyte containing different additives including sand, aggregate, salts, carbon black and plasticiser with protruding anode and cathode metal plates. These batteries produced an initial electrical output of 1.5V and 23mA through a 10 resistor as measured using data acquisition units and a …

Influence Of The Substrate Characteristics On The Bond Behavior Of Pbo Frcm-Concrete Joints, Tommaso D'Antino, Lesley H. Sneed, Christian Carloni, Carlo Pellegrino

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Fiber Reinforced Cementitious Matrix (FRCM) composites can be employed as a valid alternative to Fiber Reinforced Polymers (FRP) composites for strengthening existing reinforced concrete (RC) structures. The weakness of FRCM-concrete joints has been reported to be at the matrix-fiber interface rather than within the concrete substrate, as is usually reported in the case of FRP-concrete joints. The experimental investigations regarding FRCM strengthening available in the literature have been performed by applying the FRCM composite onto a surface that was treated before the application, usually by grinding or sandblasting. However, the role of the substrate characteristics on the failure mechanism of …

Evolution Of Non-Metallic Inclusions In Foundry Steel Casting Processes, Marc Harris, Von Richards, Ronald J. O'Malley, Semen Naumovich Lekakh

Materials Science and Engineering Faculty Research & Creative Works

The evolution of nonmetallic inclusions was examined for 4320 steel at an industrial steel foundry. The steel was followed from electric arc furnace melting through ladle refining to final casting. Timed sampling was performed at all stages of the process. Samples were analyzed using an automated SEM/EDS system. The overall evolution of oxide inclusions in terms of nucleation, growth, and flotation during liquid processing was studied using area fraction and average diameter. Chemical composition evolution was observed using a joint ternary plotting tool developed under this program. It was found that the use of zirconium as an addition for nitrogen/oxygen …

Process Development For Compression Molding Of Hybrid Continuous And Chopped Carbon Fiber Prepreg For Production Of Functionally Graded Composite Structures, Corinne Marie Warnock

Master's Theses

Composite materials offer a high strength-to-weight ratio and directional load bearing capabilities. Compression molding of composite materials yields a superior surface finish and good dimensional stability between component lots with faster processing compared to traditional manufacturing methods. This experimental compression molding capability was developed for the ME composites lab using unidirectional carbon fiber prepreg composites. A direct comparison was drawn between autoclave and compression molding methods to validate compression molding as an alternative manufacturing method in that lab. A method of manufacturing chopped fiber from existing unidirectional prepreg materials was developed and evaluated using destructive testing methods. The results from …

Molecular Dynamics Simulation Of Force-Controlled Nanoindentation, Keaton Jaramillo

Mechanical Engineering Undergraduate Honors Theses

The aim of this honors research is to develop a force-controlled nanoindentation algorithm for molecular dynamics simulation. The algorithm was tested on Silicon using the Tersoff potential and Gold using the Embedded-Atom Method (EAM) potential. The effect of varying the damping parameters that adjust the system pressure and changing run length between force iterations is explored. The force-controlled algorithm was developed and shown to be working by correlating pop-in events shown in the force versus displacement (P-h) curves to visualization software showing phase transformation or dislocation events in the sample.

Polyacrylonitrile Copolymers: Effects Of Molecular Weight, Polydispersity, Composition, And Sequencing On Thermal Ring-Closing Stabilization, Jeremy D. Moskowitz

Dissertations

Controlled polyacrylonitrile (PAN)-based carbon fiber precursors with defined molecular weights, polydispersities, compositions, and architectures have been prepared for their study on thermal ring-closing stabilization behavior. PAN and its copolymers of number average molecular weights exceeding 170,000 g/mol were successfully synthesized via low temperature reversible addition-fragmentation chain transfer (RAFT) polymerization. RAFT polymerizations of PAN-based precursors were compared to conventional free radical solution polymerizations with a focus on the effects of molecular weight and polydispersity on structural evolution and cyclization efficiency. When RAFT polymerization was extended to copolymers, it was found that RAFT copolymers achieved greater cyclization intensities and improved thermal stability …

A Comparison Of The Bond Behavior Of Pbo-Frcm Composites Determined By Double-Lap And Single-Lap Shear Tests, Lesley Sneed, T. D'Antino, C. Carloni, C. Pellegrino

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This paper presents the results of an investigation on the bond behavior and stress-transfer mechanism of polyparaphenylene benzo isoxazole (PBO) fiber-reinforced cementitious matrix (FRCM) composites bonded to a concrete substrate using double-lap and single-lap shear tests. Results of double-lap shear tests with different composite bonded lengths and widths are presented and compared with those from single-lap shear tests previously reported by the authors. The idealized load response developed from single-lap shear tests is found to characterize the response of the composite in double-lap shear tests, although with a few key differences. With the double-lap shear test, load redistribution among the …