Date of Award

Spring 5-9-2022

Degree Type

Dissertation

Degree Name

Doctor of Philosophy in Civil Engineering

Department

Civil and Environmental Engineering

First Advisor

Allena, Srinivas

Second Advisor

Khan, Lutful

Third Advisor

Owusu-Danquah, Josiah

Subject Headings

Civil Engineering

Abstract

Ultra-High Performance Concrete (UHPC) is an advanced concrete material with superior mechanical strength, high tensile ductility, and exceptional durability, including negligible permeability. Despite these excellent material properties, the use of UHPC in structural applications is limited because of the high cost of commercially available UHPC products. Therefore, developing non-proprietary UHPC mixtures using local materials is a viable way to reduce the initial cost of UHPC. In this research, sustainable and cost-effective UHPC mixtures were developed using locally sourced materials so that UHPC may be more affordable to a wider variety of applications. Specifically, locally available Type I-II cement, local sand with a top size of 4.75 mm (0.187 inch), high range water reducing admixture, domestic steel fibers, and Class F fly ash were used in this research. These material selections improved the sustainability of UHPC. Two final mixtures (plain and fiber reinforced) were recommended as the UHPC mixtures. The greatest compressive strengths obtained in this research were 138.1 MPa (20,030 psi) for plain UHPC and 165.8 MPa (24,030 psi) for fiber reinforced mixture. The greatest flexural strengths were 12.95 MPa (1,230 psi) and 14.35 MPa (2,080 psi) for plain and fiber reinforced UHPC, respectively. After developing the UHPC mixtures, physical properties: drying shrinkage and permeable porosities of plain and fiber reinforced mixtures were investigated. The drying shrinkage of plain UHPC was greater than that of fiber reinforced UHPC by 27%. The lowest permeable porosities obtained were 2.4% and 2.6% for plain and fiber reinforced mixtures, respectively. In addition to mechanical and physical properties, the durability of UHPC mixtures was also studied. Rapid chloride permeability testing was performed on plain UHPC which showed very low chloride ion penetrability. Resistance of plain and fiber reinforced UHPC mixtures to freeze-thaw cycles was studied and observed no damage due to frost action with a durability factor of 100. Additionally, sulfate resistance of the final two mixtures was evaluated by submerging the specimens under 5% sodium sulfate for one year. The maximum expansions in plain and fiber reinforced specimens were 0.07% and 0.06%, respectively, which indicated excellent resistance to sulfate attack.

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