Date of Award
Master of Science
AN ABSTRACT OF THE THESIS OF NAVIN PAIJA, for the Master of Science degree in CIVIL ENGINEERING, presented on 04/06/2017, at Southern Illinois University Carbondale. FEASIBILITY STUDY OF USING GROUND BOTTOM ASH IN GEOPOLYMER CONCRETE MAJOR PROFESSOR: Dr. Sanjeev Kumar Dr. Manoj K. Mohanty United States alone has about three quarters of the accessible worldwide reserve of coal. There are about 511 coal-powered electric plants and generates about 33% of the nation’s electricity. The combustion of coal results in a large number of solid waste materials known as coal combustion byproducts (CCBs) that are stored in landfill or ponds. These are easily accessible and with proper research it can be put into beneficial use. Today concrete is the second most consumed substance after water. Concrete, a composite material made of a binder in combination with coarse and fine aggregate, is used in foundations and structures of buildings, bridges, roads, dams. Cement is the most widely used binder for concrete, however, research has shown that a single cement industry produces approximately 5% of global CO2 emissions, and one ton of Portland cement emits approximately one ton of CO2. This emission of CO2 is one of the main reasons for global warming and has detrimental impacts on environment. The possibility of using fly ash and bottom ash as an alternative to cement as a binder to produce sustainable concrete is investigated in this study. The process of geopolymerization includes the reaction of ash and an alkali activated solution made of diluted sodium silicate and sodium hydroxide. The initial objective of this study was to produce fly ash geopolymer concrete which has a strength comparable to that of cement concrete. However, later the possibility of bottom ash as a binder material for geopolymer production was also studied. During this study, the strength of conventional mortar with 10%, 20%, and 30% cement replacement with fly ash and bottom ash was experimented and compared with strength of cement mortar. The test results showed that with increase in the fly ash and bottom ash replacement the strength of the mortars decreased, moreover, the mortars that was replaced by bottom ash produced better results than that of the fly ash replacement. Also, the effect of increase in the ratio of sodium silicate to sodium hydroxide ratio on the strength of geopolymer mortar is studied. Sodium silicate to sodium hydroxide ratio of 1.5, 2.5, and 3 is used in this ratio, and the test results showed that with the increase in this ratio the compressive strength of geopolymer mortar also increased. Similarly, different combinations of fly ash and bottom ash is used to produce geopolymer mortars. The results showed that geopolymer mortar with higher bottom ash content produced better results. The effect of ground fly ash and bottom ash on the compressive strength of geopolymer mortar is also studied. The test result showed that with increase in fineness of fly ash and bottom ash, there was slight improvement in the strength.
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