Structural Materials Commons^™

A Maximum Energy Release Rate Computational Framework For Fatigue Crack Trajectory And Life Prediction Under Mixed-Mode Proportional And Nonproportional Loading, Nahla Helmy Matar

Theses and Dissertations

The problem of mixed-mode fatigue crack growth has been a persistent research challenge. The determination of fatigue crack propagation direction directly impacts the safety and integrity of components and structures, making it crucial in various industrial applications, including welded drilling pipes, aerospace, and automotive engineering. Unlike uniaxial loading, mixed-mode cracks tend to change direction frequently (kinking), and nonproportional loading adds to the complexity of the problem. This research aims to estimate the crack propagation direction and fatigue crack life in linear elastic materials subjected to mixed-mode (I+II) loading conditions under proportional or non-proportional cyclic loading. Numerical software was developed based …

Development Of A Novel Innovative Umbrella Falsework System For Concrete Slabs, Abdelazem Hashim

Theses and Dissertations

Formwork is one of the major elements that contribute to the cost and duration of concrete building projects. This is why optimizing such an element can lead to huge savings to all parties involved in the construction projects. With contractors facing huge challenges in such a competitive industry and employers seeking the least price and least duration for their projects, contractors are constantly under the obligations of finding the best alternatives to deliver their projects in terms of both time and money. Therefore, the main aim of this research project is to develop a falsework system, where the falsework system …

Metal-Free Nitrogen-Enriched Graphitic Carbon Nitride Architectures For Advanced Supercapacitor Energy Storage: Design, Synthesis, And Electrochemical Performance Optimization, Loujain Gamal Mohamed

Theses and Dissertations

Abstract

This thesis addresses the urgent global requirement for efficient energy storage materials by developing and characterizing advanced graphitic carbon nitride (g-C3N4)-based electrode materials for supercapacitors. A facile, low-cost thermal polymerization method produces 2D nitrogen-rich GCN nanosheets exhibiting excellent electrochemical stability and wide voltage windows, enabling symmetric devices with 19.33 Wh/kg energy density and remarkable cycling stability over 21,000 cycles. To overcome intrinsic limitations of pristine GCN, a 3D/2D metal free composite with bio-derived carbon (Bio-Cx) is synthesized, delivering high capacitance, wide potential windows, and ultrahigh energy density of 53.72 Wh/kg in asymmetric configurations paired with mesoporous nitrogen-doped carbon (MPNDC). …

Copper Metal Organic Framework-Based Nanomaterial For Non-Enzymatic Glucose Electrochemical Sensor, Sameha Mohamed Sadek

Theses and Dissertations

This thesis examines the development of non-enzymatic glucose sensors by engineering advanced electrode materials based on metal-organic frameworks (MOFs). Conventional enzymatic glucose sensors, although widely used, suffer from inherent limitations, including poor long-term stability, narrow operating conditions, and sensitivity to environmental factors, due to their reliance on biological enzymes. Non-enzymatic sensors offer a more robust alternative by enabling direct electrochemical oxidation of glucose on engineered electrode surfaces. MOFs represent a highly tunable class of hybrid materials with structural and chemical features that are ideal for sensor applications, including a high surface area, tailored porosity, and excellent thermal and chemical stability. …

Partial Replacement Of Ordinary Portland Cement In Concrete By Limestone Calcined Clay (Lc2), Merna Abdelaziz

Theses and Dissertations

Limestone calcined clay (LC2) technique is a new approach that could address the environmental problem corelated with the construction industry due to its vital reliance on the ordinary Portland cement in its various applications. LC2 technique involves partial replacement of the OPC in concrete by limestone and calcined kaolinite clay with a ratio of 1:2 respectively. The main advantage of this technique is its high applicability due to its direct application on site. This study investigated the applicability of incorporating the LC2 technique in the construction industry. Three replacement percentages of OPC by LC2 in concrete were explored, which are …

A Comparative Study Between Soft Structures And Hard Structures For The Protection Of Egypt’S Coastlines Against Climate Change, Donia Eldwib

Theses and Dissertations

Coastal communities worldwide face unprecedented threats from climate change, with rising sea levels, increased storm intensities, and accelerated coastal erosion posing significant risks. Egypt, with over 3,000 kilometers of coastlines along the Mediterranean and Red Seas, it is particularly vulnerable due to its densely populated and economically critical low-elevated coastal zones. With the Mediterranean Sea, and the Nile Delta specifically under huge threats, this study examines the different coastal protection strategies used to address these climate change impacts. Different coastal protection structures have been used throughout the years starting with the well-known hard structures moving on to greener alternatives such …

Thermal Insulation And Fire Protection Plaster For Frp System Incorporating Aerogel Nanoparticles And Phyllosilicates, Athnasious Ghaly

Theses and Dissertations

For more than two decades, new innovative materials have been introduced to the market such as nano materials that can be utilized for their high performance in different aspects of the construction industry. Structural repair and strengthening is one of the most demanding fields in the construction industry for innovative and high-performance materials due to its specialty. Time, quality, economy, and sustainability are the main factors that control this field, and for that, new systems keep being introduced to the market to reduce the time of repair and enhance its efficiency. Fiber Reinforced Polymers (FRP) Systems are the most advanced …

Mechanical And Electromagnetic Properties Of Incorporating Graphene Oxide In Cementitious Mixtures, Cherif Khalil

Theses and Dissertations

This multidisciplinary study aimed at investigating the impact of incorporating graphene oxide (GO) on the mechanical properties and electromagnetic (EM) shielding effectiveness of cementitious mixtures, as well as critically examining the mechanism with which GO affects their microstructure properties. Analysis of the literature review showed that there are discrepancies in reporting the impact of GO on the mortar mix. Consequently, this study focuses on exploring the cause for such discrepancies and identifies three main factors which are thoroughly investigated. The factors were the different sonication energies applied to the GO (Shear Mixing, 1.5 kJ/ml, 3 kJ/ml and 6 kJ/ml), the …

Design And Fabrication Of Nanostructured Electrodes For Complementary Electrochemical And Photoelectrochemical Water Splitting, Kholoud El Sayed Abousalem

Theses and Dissertations

Designing highly active, durable, and nonprecious electrodes for overall water splitting is of urgent scientific importance to realize sustainable hydrogen production. Accordingly, the need to search efficient energy production systems is of crucial necessity. In this thesis, two various systems for sustainable hydrogen production have been reported using electrochemical and photoelectrochemical pathways. In the first part of the thesis, electrochemical water splitting involving both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) has been established. To this end, an innovative approach is demonstrated to synthesize flower-like 3D homogenous trimetallic Mn, Ni, Co phosphide catalysts directly on nickel foam via …

Assessment Of Carbon Dioxide Emission And Its Impact On High-Rise Mixed-Use Buildings In Egypt, Ahmed Salah Hamza

Theses and Dissertations

With Egypt's vision of 2030 focusing on sustainable development with a true emphasis on Carbon Dioxide (CO₂) emission reduction in the newly built cities and high-rise buildings, efforts are exerted on various levels towards accomplishing the vision’s goals. This is achieved through multiple tools and models associated with aiding the reduction of carbon emissions, yet not a clear one was introduced for the mixed-use buildings in Egypt.

Through this work, a significant gap was identified with respect to high-rise buildings carbon emission assessment in Egypt. This was a main driving force for this work in an attempt to …

Experimental Investigation Of Natural Fiber Reinforced Composite, Irene Samy Fahim

Theses and Dissertations

There is a growing use of polymers in different applications worldwide. This phenomenon resulted in an enormous increase in the amount of plastic waste. These wastes have significant impacts on the environment including pollution and depletion of resources. Recycling plastic waste and reusing it helps in alleviating environmental degradation. The amount of recycled plastics all over the world not utilized is huge. U.S.A recycled 5.7% of the total plastics generated and Western Europe recycled 39% of total amount of plastics consumed [1]. This research studies the potential usage of virgin and recycled polymer reinforced with natural fiber such as rice …

Abrasion Resistance Of Concrete Made With Various Types Of Aggregates, Mohamed Hamada Rashwan

Archived Theses and Dissertations

No abstract provided.

Guidelines For The Application Of Recycled Concrete Aggregate In The Egyptian Construction Industry, Ahmed Moustafa Essam Aly Kamel

Archived Theses and Dissertations

Construction industry is one of the most important fractions of economy worldwide. This industry consumes enormous amounts of raw materials and produces considerable waste. The optimization of construction material usage not only saves costs but also can significantly contribute towards sustainable development. The concept of recycling the construction and demolition rubble is being addressed in this study as a solution. The recycling of concrete, resulting from both the construction activities and the demolition activities, in order to be used as a source of aggregate is being focused upon in this study. Although the idea of using recycled concrete has been …