Dissertation
ENVIRONMENTALLY FRIENDLY PERVIOUS CONCRETE MADE OF 100% FLY ASH BINDER AND ENABLED BY GRAPHENE OXIDE
Doctor of Philosophy (PhD), Washington State University
01/2018
Handle:
https://hdl.handle.net/2376/111239
Abstract
An environmental friendly pervious concrete was developed by using fly ashes as the sole binder modified by the graphene oxide (GO). The density, void ratio, mechanical strength, Young’s modulus, infiltration rate, deicer salt scaling and degradation resistance of this pervious concrete were studied. The test results indicated that the addition of 0.03% GO (by weight of fly ash) significantly increased compressive strength, split tensile strength, Young’s modulus and deicer salt scaling and degradation resistance of the fly ash pervious concrete. This innovative fly ash pervious concrete showed a comparable performance to the Portland cement pervious concrete. The hydration precursors, morphology, elemental composition, minerology and chemical structure and ordering of GO-modified fly ash geopolymer were investigated by means of Raman spectroscopy, SEM/BSE, EMPA, XRD/TGA and 29Si/27Al MAS-NMR, respectively, to unravel the role of GO. The experimental results suggested that GO regulated the Ca/Si, Si/Al and Ca/(Si+Al) mole ratios to facilitate the formation of fly ash hydrates with improved mechanical strength, as GO showed the ability to selectively affect the distribution of different hydration precursors. GO also promoted the formation of low quartz and jennite-like hydrates. Overall, the NMR study showed that GO improved the polymerization degree of fly ash geopolymer by increasing the total Q3 and Q4 Si-tetrahedrons. A fly ash based pervious concrete could not only reduce the demand for Portland cement, but also divert the fly ash from waste stream, which otherwise poses a substantial environmental risk. Novel use of such ashes as a cementitious binder in the pervious concrete can result in cost and energy savings and reduce greenhouse gas emissions. The use of nanotechnology relaxes the restriction on using fly ashes in concrete, without sacrificing the performance of concrete. This study also reveals the possible role of GO in the hydration of fly ash and help to achieve enhanced understanding of GO-modified fly ash pervious concrete at the microscopic level.
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Details
- Title
- ENVIRONMENTALLY FRIENDLY PERVIOUS CONCRETE MADE OF 100% FLY ASH BINDER AND ENABLED BY GRAPHENE OXIDE
- Creators
- Gang Xu
- Contributors
- Xianming Shi (Advisor)Balasingam Muhunthan (Committee Member)Pizhong Qiao (Committee Member)Yuehe Lin (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Civil and Environmental Engineering
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 255
- Identifiers
- 99900581508501842
- Language
- English
- Resource Type
- Dissertation