Ankit Kothari, Hans Hedlund, Mirja Illikainen, Andrzej Cwirzen, Effects of sodium nitrate and OPC-GGBS concrete mix composition on phase transition of pore water at subzero temperatures, Construction and Building Materials, Volume 327, 2022, 126901, ISSN 0950-0618, https://doi.org/10.1016/j.conbuildmat.2022.126901
Effects of sodium nitrate and OPC-GGBS concrete mix composition on phase transition of pore water at subzero temperatures
|Author:||Kothari, Ankit1; Hedlund, Hans1,2; Illikainen, Mirja3;|
1Building Materials, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, 97187 Luleå, Sweden
2Skanska Teknik AB, Skanska Sverige AB, 40518 Göteborg, Sweden
3Fiber and Particle Engineering Research Unit, Faculty of Technology, University of Oulu, P.O. Box 4300, 90014 Oulu, Finland
|Online Access:||PDF Full Text (PDF, 8.4 MB)|
|Persistent link:|| http://urn.fi/urn:nbn:fi-fe2022051034116
|Publish Date:|| 2022-05-10
Lowering the freezing temperature of the mixing water is crucial for concrete works at subzero temperatures. In this study, formation of ice was examined for various pastes and concretes of OPC-GGBS based, while exposed to a constant temperature of −15 °C. Sodium nitrate antifreeze admixture was added as 0, 6, 10, 15, 20, 25, 30 wt% by the total binder amount. The ice formation and its effects on the binder matrix microstructure was studied using differential scanning calorimetry (DSC), ultrasonic pulse velocity (UPV) and Scanning Electron Microscopy — Energy Dispersive Spectrometry (SEM-EDS). Several curing procedures were applied to samples before commencing tests. Results showed that, addition of 25 wt% of the sodium nitrate caused the most extensive delay of the ice growth. Mixes containing less admixture showed an increasing amount of the forming ice which in some cases lead to the development of the false strength. The hydration rate has been the highest for the mix with 25 wt% of the sodium nitrate and tended to be limited at lower additions. The porosity of the hydrated binder matrix tended to be lower for mixes characterized by a lower amount of the forming ice. In general, application of above freezing temperature resulted in resuming of the hydration process that led to densification of the microstructure and strength increase. This trend was more pronounced for mixes having lower amounts of the formed ice.
Construction & building materials
|Type of Publication:||
A1 Journal article – refereed
|Field of Science:||
216 Materials engineering
116 Chemical sciences
215 Chemical engineering
This research project “ARCTIC-ecocrete” is funded by Swedish organization—Region Norbotten and European union’s—Interreg Nord.
© 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).