Author

James Wong

Date on Master's Thesis/Doctoral Dissertation

5-2016

Document Type

Master's Thesis

Degree Name

M. Eng.

Department

Civil and Environmental Engineering

Committee Chair

Sun, Zhihui

Committee Co-Chair (if applicable)

McGinley, William

Committee Member

McGinley, William

Committee Member

Hieb, Jeffrey

Author's Keywords

superabsorbent polymer; cement paste

Abstract

Rheological properties are the properties typically reference flow properties of concrete and are related to processing, construction, and setting. The purpose of this research was to investigate the influence of superabsorbent polymers (SAP) and superplasticizer (SP) on rheological properties, specifically of cement pastes with 0.35, 0.45 and 0.55 water-to-cement ratios (w/c), SAP water replacement dosages of 0%, 5%, 10%, 15%, 20% and 25% were tested. Tests included rheological measurements of yield stress, viscosity using the Bingham equation and the flow behavior index using Herschel-Bulkley equation. Slump diameter tests were used to measure flow of the cement pastes. Comparisons of slump diameters were made with regular cement pastes, pastes with SAP and SP using 0.45 w/c as a reference paste. Heat of hydration tests were also conducted to measure heat and energy produced during the hydration of cement pastes containing SAP.

The research from this study found high water-to-cement ratios in plain pastes produced lower yield stress, viscosity and flow behavior index values compared to low water-to-cement ratio plain pastes. Adding SAP was found to increase the viscosity of the paste, however, the influences of SAP on yield stress was found to depend on the w/c ratio. It was also found that when superplasticizer is used, the yield stress is reduced significantly, however, it only has slight influence on viscosity. The slump diameter measurements decreased with increasing SAP dosage. The calorimetric measurements indicate that the addition of SAP does not change the hydration mechanism of the pastes.

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