Date of Award
Master of Science (MS)
Daba S. Gedafa
Concrete usage is increasing rapidly; subsequently, the industry's carbon footprint is increasing. Coal Bottom Ash (CBA)/Boiler Slag Bottom Ash (BS) is a byproduct of coal-burning power plants. This material can replace fine aggregate in concrete to reduce global natural material depletion. Using CBA/BS in the construction industry will reduce the technical and economic problems associated with power plants by reducing solid waste. This project's objective was to determine whether using new sustainable materials, such as CBA/BS, in concrete will reduce natural raw material usage and energy consumption. This study included three projects: comparing increased CBA/BS content to the three-control projects and determining the optimum content based on the compressive strength. The finding of this project indicates that 50% CBA/BS is the optimum content, which reduces fine aggregate usage in a concrete mix by 50% and maintains equivalent to or better concrete strength than the control. The CBA optimum content had a unit weight lower than the controls for all three projects, which makes the CBA lightweight concrete. Increasing CBA content decreases the slump value and the air content, possibly due to the higher water demand of CBA. Therefore, a superplasticizer was used to obtain the desired workability. CBA concrete compressive strength increased over time due to the CBA pozzolanic reaction that occurs later in the hydration reaction. However, using nano clay increased the pozzolanic reaction of CBA content at an early age. It increased CBA optimum content to 80% after 28 days of curing. Therefore, CBA can significantly reduce natural material usage and environmental harm by reducing CBA/BS waste disposal and improving concrete performance.
Menda, Samrawit, "Determining Optimum Coal Bottom Ash Content For Sustainable Concrete Infrastructure" (2022). Theses and Dissertations. 4548.
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