Author ORCID Identifier

https://orcid.org/0009-0005-9144-5930

Date Available

10-31-2024

Year of Publication

2024

Degree Name

Master of Science (MS)

Document Type

Master's Thesis

College

Arts and Sciences

Department/School/Program

Earth and Environmental Sciences (Geology)

First Advisor

Dr. Robert B. Jewell

Second Advisor

Dr. David Moecher

Abstract

Calcium sulfoaluminate (CSA) was developed in part to lessen the environmental impact of cementitious materials compared to traditional Portland cements. CSA was first put into production in the 1970s and has been undergoing various performance testing to investigate its durability. Yet to be evaluated is CSA’s response to a rapid, high temperature event. In this study, X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectrometry and scanning electron microscope imaging were used to analyze alterations in the mineralogy due to such an event. As found in previous studies, after ~125°C, ettringite has been completely dehydrated. Ettringite decomposes into bassanite and calcium carbonate while free aluminum likely bonded to hydroxides to form Al(OH)3. As temperature increased, bassanite continued to dehydrate into anhydrite. No alteration was present in samples of belite or ferrite. The decomposition of ettringite had a negative effect on the overall compressive strength of CSA cement. Due to severe alteration, CSA cement structures that have endured a rapid, high temperature event would need to be repaired or replaced.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2024.281

Funding Information

U.S. Army Corps of Engineers - Engineering Research and Development Center - 2022-2024

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