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Dissertation/Thesis Abstract

The effect of mechano-chemical activation of fly ash- nanoparticle blends on performance of cement based composites and selfconsolidating concrete
by Pradoto, Rani, Ph.D., The University of Wisconsin - Milwaukee, 2016, 145; 10124425
Abstract (Summary)

Other than water, portland cement concrete is the most used commodity. Major parts of civil and transportation infrastructure, including bridges, roadway pavements, dams, and buildings are made of concrete. Because of wide-scale applications of these important structures in different climatic zones and associated exposures, concrete durability is often of major concern. In 2013, the study of American Society of Civil Engineers (ASCE) estimated that one-third of America’s major roads are in poor or mediocre condition [1]. The same article reports that annual investments of $170 billion on roads and $20.5 billion for bridges are needed to substantially improve the condition of infrastructure. In addition to durability concerns, the production of portland cement is associated with the emissions of approximately one cubic meter of carbon dioxide per ton (plus NOx and SOx). Therefore, replacement of portland cement with supplementary cementitious material is an important trend to improve the sustainability of concrete. Indeed, the consideration of these issues as well as proper and systematic design of concrete intended for highway applications is of extreme importance as concrete pavements represent up to 60% of interstate highway systems with heavier traffic loads.

The combined principles of material science and engineering can provide adequate methods and tools to facilitate improvements to concrete design and existing specifications. Critically, durability and enhancement of long-term performance must be addressed at the design stage. Concrete used in highway pavement applications has relatively low cement content and also can be placed at low slump. However, further reduction of cement (cementitious materials) content to 280 kg/m3 vs. current specifications which require the use of 315 - 340 kg/m3 of cementitious materials for concrete intended for pavement applications and 335 kg/m3 for bridge substructure and superstructure needs a delicate proportioning of the mixture to maintain the expected workability, overall performance, and ensure long-term durability in the field. Such design includes, but is not limited to the optimization of aggregates and improvement of efficiency of supplementary cementitious materials (SCM), as well as fine-tuning of the type and dosage of chemical and air-entraining admixtures.

Self-consolidating concrete (SCC) is a new type of concrete which is characterized by its ability to fill the formwork under its own weight without the use of vibration, while maintaining the homogeneity at a very low segregation. Self-consolidating concrete can flow easily under its own weight and is characterized by near zero yield value. Therefore, the design of SCC needs to minimize yield stress parameter which is different from conventional concrete. Better understanding the workability and flow behavior of developed SCC requires the investigation of the rheological response (shear stress and viscosity) of cement pastes of the same composition as SCC. (Abstract shortened by ProQuest.)

Indexing (document details)
Advisor: Sobolev, Konstantin
Commitee: Church, Ben, Kozhukhova, Marina, Nosonovsky, Michael, Tabatabai, Habib
School: The University of Wisconsin - Milwaukee
Department: Engineering
School Location: United States -- Wisconsin
Source: DAI-B 77/10(E), Dissertation Abstracts International
Subjects: Engineering, Civil engineering
Keywords: Concrete material, Mechano-chemical activation, Nanoparticles, Self consolidating concrete, Strength, Sustainable development
Publication Number: 10124425
ISBN: 978-1-339-82533-5
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