Sandip Poudel

Date of Award

January 2023

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Civil Engineering

First Advisor

Daba Gedafa

Abstract

Cement production requires a high amount of energy and natural resources which has a high impact on the environment due to harmful gas emissions. Coal bottom ash (CBA) or Coal Boiler Slag (CBS) is the byproduct of coal-fired power plants that has pozzolanic properties. CBA or CBS can be mechanically ground to obtain Ground Coal Bottom Ash (GCBA) or Ground Coal Bottom Slag (GCBS). GCBA has the potential to replace cement in concrete which will reduce the waste in landfills, make economic benefits, preserve natural resources, and reduce health hazards. This research was performed to determine the optimum GCBA or GCBS content that can be used as a replacement for cement in concrete. In this research concrete with GCBA was compared with cement concrete for fresh, mechanical, and durability properties. Cement replaced by 10% GCBA and 5% GCBS in concrete was determined as the optimum content based on the compressive strength. The tensile strength, modulus of elasticity, and durability properties of GCBA-based concrete were better than the control at the optimum content. Also, the compressive strength of GCBA or GCBS-based mortar increased with the increase in fineness of GCBA or GCBS. The fineness of GCBA or GCBS is recommended to be within the limit mentioned in the standard ASTM C618 to enhance the properties of concrete or mortar. In the future, the research team will evaluate the mechanical and durability properties of remaining GCBA or GCBS-based concrete with or without nanomaterials compared to the cement concrete.

Keywords: Coal bottom ash, coal boiler slag, pozzolanic properties, compressive strength, durability, workability

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