Speaker: Jingyue Zhang & Amit Mondal, Transportation Graduate Students
Titles: 1. a novel divide and combine based approach to estimating mixture markov model for large categorical time series data: an application to study of clusters using multiyear travel survey data
2. synthesizing household and person-level attributes jointly for individual geographies using hidden markov model
Location: EII 322
Time: Monday 11/05/18 @ 12:20PM
Speaker: Professor Peter C. Baldwin, Department of History, College of Liberal Arts & Sciences University of Connecticut
Title: Dependence, Damage, and Displacement: Unintended Consequences of Technological Change.
Location: EII 322
Time: Monday, November 12, 2018, 12:20 – 1:10 PM
THE UNIVERSITY OF CONNECTICUT
Civil & Environmental Engineering
AILEEN VANDENBERG, B.S., B.A., M.S.
Ph.D. Dissertation
Department of Civil and Environmental Engineering
University of Connecticut
10:00 AM – Thursday, November 15, 2018
CAST 306
Advisory Committee:
Dr. Kay Wille (Major Advisor)
Dr. Nicolas Roussel (Major Co-Advisor)
Dr. Hela Bessaies-Bey (Associate Advisor)
Dr. Michael Accorsi (Associate Advisor)
Investigating High Energy Mixing in Cement-Based Materials
ABSTRACT
One of the current challenges to nano-engineering cementitious composite materials is obtaining properly dispersed nano-sized particles in the cementitious composite matrix. Properly dispersed nanoparticles can lead to an improved particle packing density, a key parameter to improving the mechanical, chemical, and sustainable properties of the cementitious composite. Broadening the particle size distributions of cementitious materials, such as ultra-high performance concrete (UHPC), to include additional nano-sized particles is a challenge that requires a better understanding of how they self-assemble in the cementitious matrix. Thus, the purpose of this research is to investigate the role mixing plays in multi-scale, multi-phase self-assembling cement-based material systems. This is achieved through three objectives. The first objective is to investigate resonant acoustic mixing, a mixing method not common to the concrete industry, and its ability to act as a high-intensive mixer. The second objective is to consider how using resonant acoustic mixing affects the assemblage of UHPC with carbon nanofiber inclusions and cement paste with carbon nanoplatelet inclusions. The third objective is to understand the origins of high-shear mixing and how it influences the development of cement hydration. To achieve these three objectives a systematic analysis is carried out that includes quantifying the mixing energy demand; analyzing surface characteristics through scanning electron microscopy, inverse gas chromatography, dynamic light scattering, and mercury intrusion porosity; and applying rheological theory to connect macroscopic properties to the fundamental properties of the materials. The results show that mixing is a very important parameter to multi-scale, multi-phase self-assembling cement-based materials and should be considered more in concrete research.
Speaker: Prof. Casey Brown, University of Massachusetts at Amherst
Title: Freshwater Resilience by Design: Water investment strategies for a changing and uncertain future
Location: IPB 203
Time: November 16th 2018 1:00 PM – 2:00 PM
University of Connecticut
Department of Civil and Environmental Engineering
Environmental Engineering Program
Yaguang Du
PhD Thesis DEFENSE
Department of Civil & Environmental Engineering
Environmental Engineering Program
University of Connecticut
10:00 A.M. – THURSDAY, NOVEMBER 29, 2018
CAST 306
Advisor Committee:
Maria Chrysochoou (Major Advisor)
Amvrossios C. Bagtzoglou (Associate Advisor)
Baikun Li (Associate Advisor)
Timothy Vadas (Associate Advisor)
Liyuan Chai (Associate Advisor)
“An investigation of the geochemical properties and treatment of soda ash Chromite Ore Processing Residue”
Abstract: In recent years, the common lime-based roasting process of chromite ore that is used to extract chromium is being replaced by alternative processes that produce less waste. Chromite Ore Processing Residue (COPR) contains high concentrations of hexavalent chromium (Cr(VI)), a human carcinogen, and is a hazardous waste that requires intensive treatment prior to disposal. China has banned the lime roasting process since 2013 and an alternative process using soda ash as roasting and complexing agent has replaced it in the larger factories. The process still produces COPR with residual Cr(VI), albeit in lower amounts. Although much is known about the properties and treatment of lime-based COPR, there are no studies in the literature on soda ash derived COPR. Accordingly, this research constitutes the first comprehensive assessment of soda ash COPR in terms of: a) chemistry, mineralogy and leaching characteristics; b) speciation of Cr(VI) in the solid; c) treatment of residual Cr(VI) using different reducing agents. The COPR sampled from a large factory in China contained 8,500 mg/kg of Cr(VI), indicating poor recovery during the leaching process. Preliminary tests indicated that approximately 90% of the Cr(VI) is water soluble, while the remaining 10% is more tightly held within the matrix and requires lowering the pH from 12.5 to 8 for release. Accordingly, all studies will be performed on two distinct COPR fractions: “original” COPR, with the material tested as-is, and “column leached” COPR, which has been subjected to DI water leaching to remove all water-soluble Cr(VI) prior to further studies. The proposed research is divided into three parts: The first part is a leaching and modeling study of the two COPR types, studying the leaching of major and trace elements as a function of pH. The second part utilized microstructural spectroscopy techniques (micro-X-ray Fluorescence, Absorption and Diffraction) to study the mineral hosts of Cr(VI), information used to optimize treatment. Finally, the third part evaluated the reduction of residual Cr(VI) in COPR using calcium polysulfide, nano-scale zerovalent iron stabilized with gree tea extract (GT-nZVI), and pyrolysis remediation with miscanthus mixture.
