Interactions between fluoride ions and cement paste containing superplasticizer
- Tokyo Institute of Technology, Graduate School of Science and Engineering, 2-12-1 Ookayama Meguro-ku, Tokyo (Japan)
- Shimane University, Department of Chemistry, Interdisciplinary Graduate School of Science and Engineering, 1060 Nishikawatsu, Matsue, Shimane (Japan)
- Tokyo Institute of Technology, School of Materials and Chemical Technology, 2-12-1 Ookayama Meguro-ku, Tokyo (Japan)
Fluoride compounds are used as fluxes in the low-temperature calcination of cement. Elution of fluoride ions after calcination decreases the fluidity of cement paste containing superplasticizers, but the mechanism of fluidity decrease is unclear. Authors investigated the effects of fluoride on cement pastes containing superplasticizers and the fluidity decrease mechanism. KF addition to cement paste containing a polycarboxylate- or naphthalenesulfonate-based superplasticizer increased the yield stress, the amount of adsorbed superplasticizer, and the solid-phase specific surface area. KF addition increased the amount of adsorbed superplasticizer for alite paste but not for Ca{sub 3}Al{sub 2}O{sub 6}-CaSO{sub 4} paste. Transmission electron microscopy found SiO{sub 2} fine particles after KF addition. In the absence of water, the increase in specific surface area with fluoride was larger in hydrated than in unhydrated cement. It is supposed that the fluidity decrease results from the preferential adsorption of superplasticizer on SiO{sub 2} particles generated by reactions between hydrated calcium silicate and fluoride ions.
- OSTI ID:
- 22697092
- Journal Information:
- Cement and Concrete Research, Vol. 91; Other Information: Copyright (c) 2016 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0008-8846
- Country of Publication:
- United States
- Language:
- English
Similar Records
Influence of time addition of superplasticizers on the rheological properties of fresh cement pastes
Influence of superplasticizers on the rheology and stability of limestone and cement pastes