Materials Science Research Lecture

Abstract:

With the world facing a climate crisis due to increasing CO2 emissions, there is pressing need to develop and implement sustainable construction/engineering materials across the globe. Alkali-activated materials (AAMs) are one such sustainable alternative to conventional ordinary Portland cement (OPC) concrete (up to 80-90% reduction in CO2 emissions); however, questions remain regarding the long-term performance of AAMs which is hampering implementation of this sustainable solution in the construction industry. Furthermore, for OPC-based concrete, the use of extensive clinker substitution to reduce CO2 emissions has led to changes to the underlying chemistry of the main binder gel, where it is uncertain how these novel supplementary cementitious materials augment the long-term properties (e.g., gel stability and pore structure) of the cement paste.

Here, I will outline how fundamental materials research is addressing the long-term performance unknowns of AAMs and certain OPC-based systems, where we are linking key experimental techniques with atomistic and larger length scale simulations. In the first part of this talk I will discuss how, using density functional theory calculations, we have uncovered the early stages of calcium-silicate-hydrate gel formation and the impact of aluminum and sodium on the formation mechanisms. The second part of this talk will focus on experimental determination of the chemical mechanisms occurring during formation of sustainable cements using neutron and X-ray scattering/spectroscopic techniques. Discovery of the chemical mechanisms responsible for the macroscopic properties (such as strength development and setting) is hampered by the heterogeneous and amorphous nature of these materials. However, as will be discussed in this talk, by combining key laboratory techniques with neutron and X-ray scattering/spectroscopy we have unraveled the dominant chemical mechanisms controlling the short-term behavior of a range of AAMs.

More about the Speaker:

Claire White is an Assistant Professor at Princeton University in the Department of Civil & Environmental Engineering and the Andlinger Center for Energy and the Environment. Dr White received a B.Eng. in Civil Engineering (Hons.) and a B.S. in Physics from the University of Melbourne, Australia, in 2006. Dr White completed her graduate studies in 2010 at the University of Melbourne, supported by an Australian Postgraduate Award from the Australian government. After receiving her PhD, 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.

Dr. White's research focuses on understanding and optimizing engineering and environmental materials, with an emphasis on controlling the chemical mechanisms responsible for formation and long-term degradation of low-CO2 cements. This research spans multiple length and time scales, utilizing advanced synchrotron and neutron-based experimental techniques, and simulation methodologies. Dr. White is the recipient of a number of awards including a National Science Foundation CAREER Award, the RILEM Gustavo Colonnetti Medal, and the Howard B. Wentz Jr. Junior Faculty Award.