Date of Graduation

5-2019

Document Type

Thesis

Degree Name

Bachelor of Science in Civil Engineering

Degree Level

Undergraduate

Department

Civil Engineering

Advisor/Mentor

Cameron Murray

Committee Member/Reader

Woodrow Shew

Abstract

Today the need to opt for alternative cementitious materials is growing due to environmental reasons and construction time frames that portland cement cannot always satisfy. Calcium Sulfoaluminate (CSA) cements are a strong candidate to supplement or replace portland cement in the construction field for certain applications. In the United States, CSA cement has been limited mostly to pavement repairs because of its rapid initial setting time. The chemical compound responsible for this phenomenon is the alumina. This compound and sulfate are present in larger proportions compared to portland cement. The purpose of this research is to study how the use of a retarder, citric acid specifically, affects the setting time, compression strength, and temperature behavior of cement paste made using CSA-belite cement. The analysis of the setting time was conducted by means of the Vicat test and penetration resistance test. The temperature gradient was measured with thermocouples concurrently with the setting time tests. The results showed that the setting time and the citric acid dosage (dosage range in % by weight of cement) have a linear relationship. Moreover, the increasing citric acid dosage reduces the magnitude of the temperature peak and shifts it along the time axis. The results also showed that the compressive strength at the seven-day stage increases slightly as citric acid is added to the mixture. From the compressive strength analysis, it was observed that not adding citric acid produced fractures in the cement paste samples that affected the compressive strength. The results of this research can be utilized as guidance for future research or to guide mix proportioning of concrete made with CSA cement.

Keywords

CSA cement; concrete; civil engineering; citric acid; rapid setting; setting time

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