Engineering Commons^™

Utilization Of Low-Lime Calcium Silicate In Hydrated And Carbonated Cementitious Materials, Mohammad Rakibul Islam Khan

Electronic Theses and Dissertations

This study investigated the potential application of wollastonite as a cementitious material in both hydrated and carbonated binder systems. Wollastonite is naturally occurring low-lime calcium silicate (CaO.SiO₂) mineral with a substantially lower carbon footprint compared to the ordinary Portland cement (OPC). The first part of this work presented the application of wollastonite as partial replacement of OPC in traditional hydrated cement-concrete system. Second part of this work evaluated the properties of carbonation activated binder produced using wollastonite as the primary ingredient.

For the first part of the thesis, ground wollastonite with 3.5 µm and 9 µm mean particle …

An Investigation On The Effects Of Cellulose Nanofibrils On The Performance Of Cement Based Composites, Hosain Haddad Kolour

Electronic Theses and Dissertations

Cellulose nanofibrils (CNFs) are hydrophilic biodegradable nanoparticles (typically, less than 0.2 mm in length and 20-50 nm in width) that can be extracted from various plants, trees, and recycled paper stock. Their low density, low toxicity, relatively low cost, high aspect ratio, and high specific surface enable functionalization. In this work, the effects of CNFs on selected properties of cement paste, mortar, and concrete were investigated. For the cement pastes, rheology tests using a simple rheometer showed a reduction in workability as CNF dosage increased. Free shrinkage tests showed an increase in shrinkage at high w/c ratios but a decrease …

A Laboratory Investigation Of Cement Based Materials With Cellulose Nanofibers, Parivash Takasi

Electronic Theses and Dissertations

Cellulose Nanofibers (CNFs) are used as additives in cement-based products to modify their properties. Recent studies about the effects of CNFs on cement paste showed inconsistent results for several different important properties, including compressive strength and free shrinkage. There is reason to believe that the unsystematic results of the compressive strengths were affected by the lack of uniform dispersion of CNFs. As a potential remedy, two different mixing methods were applied. The first method used a basic mixer, but aggregates were added to the cement paste mixture to improve the blending process. The second method utilized a high-speed shear mixer …

Modeling Response Of Water Quality To Land-Use And Climate Change In Lake Auburn, Me, Nicholas Messina

Electronic Theses and Dissertations

Lake Auburn, Maine, USA, is a historically unproductive lake that has experienced multiple algal blooms since 2011. The lake is the water supply source for a population of ~60,000. We modeled past temperature, and concentrations of dissolved oxygen (DO) and phosphorus (P) in Lake Auburn by considering the watershed and internal contributions of P as well as atmospheric factors, and predicted the change in lake water quality in response to future climate and land-use changes. A stream hydrology and P-loading model (SimplyP) was used to generate input from two major tributaries into a lake model (MyLake) to simulate physical mixing, …

Potential Value-Added Utilization Of Wood Ash In Construction Materials, Naveen Saladi

Electronic Theses and Dissertations

Wood ash is a byproduct from biomass power plants. Most of the wood ash is currently being disposed of as landfilling material that causes severe economic and environmental concerns. This project focuses on the feasibility of using this wood ash in construction materials. Wood ash was found to contain varieties of mineral phases including calcium carbonate, calcium aluminate, and quartz. Based on the chemical composition, the efficacy of wood ash (i) as supplementary cementitious materials (SCM), (ii) in the controlled low strength materials (CLSM) production and (iii) Portland cement production was evaluated.

Wood ash with adequate pozzolanic properties can be …

Investigating The Time-Dependent And The Mechanical Behavior Of Wood Plastic Composite Lumber Made From Thermally Modified Wood In The Use Of Marine Aquacultural Structures, Murtada A. Alrubaie

Electronic Theses and Dissertations

Wood Plastic Composite (WPC) lumber based on a patent-pending formulation is being explored for use in the manufacture of an aquaculture fish cage structure (Aquapod net pen cage), as an alternative to the current high density polyethylene (HDPE) lumber. The use of WPC lumber in structural applications in marine environments requires a comprehensive effort to understand the material viscoelastic behavior and the structural performance of the WPC lumber in marine environments where the WPC lumber is exposed to the combined effect of saltwater immersion and temperature (hygrothermal). The evaluation of the viscoelastic behavior of WPC lumber in marine environments was …

Tidal And Subtidal Processes At The Mouth Of A Macrotidal Estuary, Rachel Chambers

Electronic Theses and Dissertations

Secondary flows and mixing have been shown to influence sediment transport, the vertical salinity gradient, and the exchange flow in estuaries. Typically, these hydrodynamic properties are investigated with respect to time and depth and their variability across the estuary is neglected. However, recent studies have shown that secondary flows and mixing, along with mechanisms that influence them, can exhibit lateral variability. Additionally, the variability of these hydrodynamic properties has not been studied in macrotidal estuaries, where the increased tidal forcing could affect the strength and cross channel variability.

There are two primary objectives of this thesis. The first objective is …

Perspectives On Water Resources Risk, Policy, And Stewardship, Anne Marie Lausier

Electronic Theses and Dissertations

Water management approaches have historically optimized water for human use and placed lower emphasis on the relationship between ecosystems and humans. Despite efforts to balance human and ecosystem needs, existing management approaches tend to prioritize some needs, knowledges, and values over others. Natural and anthropogenic changes pose challenges to water governance institutions due to policy inflexibility, and may lead to ecosystem degradation, water stress, and conflict among water users. This work seeks to redress these shortcomings through three scholarly contributions. First, a conceptual framework for Water Resources Stewardship is developed in support of equitable and adaptive solutions under changing conditions. …

Process Optimization Of Levulinic Acid Production From Seaweeds And Its Upgrading To Tdo Oil, Maurvin Patel

Electronic Theses and Dissertations

Levulinic acid (LA) is a platform chemical and it can be upgraded to various products like bio-oil. The acid hydrolysis of cellulose is a widely researched pathway to make LA. However, investments to produce LA commercially can be subjected to risks due to feedstock price volatility and high processing costs. Such risks can be reduced by expanding the feedstock portfolio to produce LA from feedstock beyond wood and improving the energy efficiency of the process. One little investigated feedstock for production of LA is macro algae (seaweed). Seaweed is potentially attractive because it has low content of lignin or 5 …

Nawic Focus (January-March 2019), National Association Of Women In Construction - Maine Chapter Staff

Maine Women's Publications - All

No abstract provided.