Project Report

During my tenure as a 2011 EAPSI fellow at The University of Melbourne in Australia I was able to accomplish many research objectives while investigating the formation of co-fired fly ash geopolymers. Co-fired fly ash is a by-product of the co-combustion of coal with biomass, which is a rapidly growing renewable energy source. Preliminary results from research performed at Georgia Tech (where I am currently working to obtain a PhD in Civil Engineering) revealed similar elemental compositions and physical attributes between co-fired fly ash and coal fly ash, rendering it a suitable option for geopolymer synthesis. Geopolymers are formed by alkali-activating solid fly ash aluminosilicates to produce a mineral binder that has broad applications in the construction field as a cost-effective and less carbon-intensive alternative to ordinary portland cement (OPC) concrete. Dr. John Provis and Dr. Susan Bernal, my EAPSI advisors in the Department of Chemical and Biomolecular Engineering, were both instrumental in my development of geopolymer mixes and subsequent analyses over the course of the fellowship. This multidisciplinary collaboration aimed to not only develop these novel co-fired fly ash geopolymers, but also to understand the science behind their structure at multiple scales. The first task of this research was to create viable geopolymer mixes. Ash samples brought from the U.S. including two co-fired fly ashes with differing biomass sources and co-firing weight percentages and one commercially available coal fly ash (typically used to replace cement in OPC concrete) were used in this research. Chemical activating solutions were chosen to account for the unique properties of the co-fired fly ash (e.g., some of the samples had unfavorable high carbon contents). All of the ashes were successfully geopolymerized through altering various parameters in the mix design. The wide spectrum of binder compositions developed during this process were then analyzed using advanced techniques to understand the mechanisms of synthesis. Dilatometry was used to assess the reactivity of the fly ash as well as the mechanical performance of each mix. A Fourier transform infrared spectra of each sample was measured at two ages to determine the degree of polymerization and the extent of activation of each matrix. Lastly, X-ray diffraction was used to identify the crystalline phases present in each sample before and after geopolymerization. This research uncovered some of the fundamental properties of this novel material. However, more research will need to be conducted on this new binder before large-scale implementation can be achieved for future sustainable infrastructure projects. The broader impacts resulting from geopolymer technology reach far outside the world of academia. The use of geopolymers can reduce carbon emmisions by eliminating the need for cement while reusing an industrial by-product to rebuild our nation’s failing infrastructure. Specifically related to this project, multiple outreach activities were developed to target underrepresented groups in science and engineering. In addition to research activities, this project supported a variety of cultural experiences. I made it a goal to fully explore the rich Australian culture by visiting as many places as possible including Melbourne, Sydney, Adelaide, the Great Ocean Road, and the Great Barrier Reef. I hope to make it back someday to experience more of the amazing adventures Australia has to offer. Yet for now, I am sure that both the research and life experiences I gained as an EAPSI fellow has helped prepare me for a better future.

National Science Foundation (NSF)
Office of International and Integrative Activities (IIA)
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Carter Kimsey
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Shearer Christopher R
United States
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