TY - JOUR
T1 - Influence of temperature on rheological properties during early-stage geopolymerization
AU - Brandvold, Allison S.
AU - Kriven, Waltraud M.
N1 - Publisher Copyright:
© 2023 The Authors. Journal of the American Ceramic Society published by Wiley Periodicals LLC on behalf of American Ceramic Society.
PY - 2023
Y1 - 2023
N2 - Metakaolin geopolymers have gained much interest as a large-scale, 3D printable material. It is well known that increasing temperature can expedite the geopolymerization reaction, but little is known about how the temperature variability of the printing environment can influence the rheology of fresh geopolymer pastes. In this study, the influence of temperature on the viscosity of potassium geopolymer pastes was investigated under constant shearing at rates of 25, 50, or 100 s−1, yield stress measurements, and oscillatory motion. The temperature range examined was 5°C–55°C, in systematic 5°C increments. It was found that temperatures above 30°C resulted in lower starting viscosities compared to colder temperatures, but eventually exhibited an exponential increase in viscosity as the geopolymerization chemical reaction became dominate. In addition, a higher shear rate delayed, but did not stop, the exponential increase in viscosity from occurring. Yield stress values also reflected an upward trend with increasing temperatures after a 30-min temperature soak. Lastly, oscillatory measurements indicated that viable printing times for 50°C or above were as little as 50–60 min total and were compared to Vicat needle testing. Overall, the influence of temperature on rheological properties could be used to manipulate the geopolymer viscosity for optimum printing conditions.
AB - Metakaolin geopolymers have gained much interest as a large-scale, 3D printable material. It is well known that increasing temperature can expedite the geopolymerization reaction, but little is known about how the temperature variability of the printing environment can influence the rheology of fresh geopolymer pastes. In this study, the influence of temperature on the viscosity of potassium geopolymer pastes was investigated under constant shearing at rates of 25, 50, or 100 s−1, yield stress measurements, and oscillatory motion. The temperature range examined was 5°C–55°C, in systematic 5°C increments. It was found that temperatures above 30°C resulted in lower starting viscosities compared to colder temperatures, but eventually exhibited an exponential increase in viscosity as the geopolymerization chemical reaction became dominate. In addition, a higher shear rate delayed, but did not stop, the exponential increase in viscosity from occurring. Yield stress values also reflected an upward trend with increasing temperatures after a 30-min temperature soak. Lastly, oscillatory measurements indicated that viable printing times for 50°C or above were as little as 50–60 min total and were compared to Vicat needle testing. Overall, the influence of temperature on rheological properties could be used to manipulate the geopolymer viscosity for optimum printing conditions.
KW - Vicat needle
KW - geopolymers
KW - temperature
KW - viscosity
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U2 - 10.1111/jace.19484
DO - 10.1111/jace.19484
M3 - Article
AN - SCOPUS:85174022190
SN - 0002-7820
JO - Journal of the American Ceramic Society
JF - Journal of the American Ceramic Society
ER -