Ettringite-based binder from ladle slag and gypsum : the effect of citric acid on fresh and hardened state properties
Nguyen, Hoang; Kinnunen, Päivö; Gijbels, Katrijn; Carvelli, Valter; Sreenivasan, Harisankar; Kantola, Anu M.; Telkki, Ville-Veikko; Schroeyers, Wouter; Illikainen, Mirja (2019-07-01)
Nguyen, H., Kinnunen, P., Gijbels, K., Carvelli, V., Sreenivasan, H., Kantola, A. M., … Illikainen, M. (2019). Ettringite-based binder from ladle slag and gypsum – The effect of citric acid on fresh and hardened state properties. Cement and Concrete Research, 123, 105800. https://doi.org/10.1016/j.cemconres.2019.105800
© 2019 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/).
https://creativecommons.org/licenses/by-nc-nd/4.0/
https://urn.fi/URN:NBN:fi-fe2019070222640
Tiivistelmä
Abstract
The retardant effects of citric acid on the properties of ettringite binders are not yet fully understood. This investigation provides insights into the effects of citric acid on both the fresh and hardened state properties of the binder produced from the hydration between ladle slag and gypsum (LSG). The results revealed that LSG’s initial setting time could be controlled via different citric acid contents and could range from 20 min to 2 h. Citric acid is effective at relatively high dosages; in its absence, ettringite formed almost immediately directly following exposure to water. The presence of citric acid alters the hydration reactions in LSG. AFm was found to be one of main hydration products; citric acid promoted the conversion from ettringite to monosulfate, detected by using solid-state ²⁷Al magic-angle spinning nuclear magnetic resonance spectroscopy. In addition, citric acid increased the compressive strength of LSG mortars by up to 45%.
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