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Seminar 5/7/2014 - Claire E. White, Princeton University: Engineering Sustainable Cements at the Mesoscale

Abstract: Understanding the formation mechanisms and phase stability of amorphous aluminosilicates is extremely important for a range of geological and industrial processes including zeolites, glasses and low-CO2 geopolymer cements. However, due to their disordered nature at the atomic length scale it is difficult to elucidate the exact structural rearrangements occurring during formation. Here, two state-of-the-art theoretical and experimental approaches will be outlined, and their suitability for studying amorphous aluminosilicates will be discussed.

Novel modeling and simulation methods across length scales are emerging in the research community, yet it remains difficult to span length scales without a significant compromise in accuracy. Coarse-grained Monte Carlo simulations used in conjunction with quantum chemical thermodynamic calculations is a relatively new methodology capable of spanning the atomic and nanoscale (toward the mesoscale). Here, it will be applied to modeling (i) silicate speciation (oligomerization) as a function of concentration at high pH, and (ii) the geopolymerization reaction, revealing new structural insight on the formation mechanisms taking place. The advantages and disadvantages of using this multiscale simulation methodology will be outlined and compared with conventional simulation approaches.

Experimental pair distribution function analysis is a powerful tool capable of elucidating the local structural motifs present in amorphous materials. This technique is well-suited for studying the structural arrangements in amorphous aluminosilicates, including glasses and cements. Here, by utilizing pair distribution function analysis it will be shown that the atomic structure of calcium-aluminum-silicate-hydrate gel (found in alkali-activated slag cements) is intrinsically different to calcium-silicate-hydrate gel known to exist in ordinary Portland cement (OPC)-based concrete. This fundamental difference (amorphous versus nanocrystalline) draws into question the suitability of OPC-based approaches (thermodynamic modeling, atomic ordering, phase formation) for studying alkali-activated cement systems.

Bio: Claire White received a B.Eng. in Civil Engineering and a B.S. in Physics from the University of Melbourne, Australia, in 2006. She completed her graduate studies in 2010 at the University of Melbourne in the Geopolymer and Minerals Processing group, supported by an Australian Postgraduate Award from the Australian government. After receiving her Ph.D., she worked as a postdoc at Los Alamos National Laboratory, and was awarded a Director’s Postdoctoral Fellowship to research the atomic structure of low-CO2 alkali-activated cements. In 2012, she was awarded the Outstanding Student Research Prize from the Neutron Scattering Society of America in recognition of her Ph.D. research contributions to neutron sciences. In August, 2013 she joined the faculty at Princeton University as an Assistant Professor in the Department of Civil and Environmental Engineering and the Andlinger Center for Energy and the Environment. Her research group focuses on understanding and optimizing engineering and environmental materials, including low-CO2 cements and amorphous carbonate-based phases. This research spans multiple length and time scales, utilizing advanced synchrotron and neutron-based experimental techniques, and simulation methodologies.

All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.

Location: Bowen Hall Auditorium

Date/Time: 05/07/14 at 12:00 pm - 05/07/14 at 1:00 pm

Category: PRISM/PCCM Seminar Series

Department: PRISM