The effect of limestone replacement in the reaction and phase assemblage evolution of two sodium sulfate activated slag cements was investigated. The slag composition and its reactivity influenced the reaction kinetics of these materials. Paste with limestone addition exhibited an acceleration in reaction kinetics, particularly for slowly reacting slags. Ettringite and an aluminium substituted calcium silicate hydrate were identified as main reaction products in these cements, independently of the slag type or limestone replacement level. No significant changes in phase assemblages were observed with limestone addition for over 365 days of testing; however, these composite cements exhibited an increased compressive strength, consistent with a refined pore structure. These results indicate that it is possible to partially replace slag by limestone in sulfate activated slag cements without changing the type of reaction products forming in these systems, while also increasing compressive strength and achieving a similar refined pore structure.
Bibliographical noteThis study was supported by the School of Civil Engineering at the University of Leeds, and the UK Engineering and Physical Sciences Research Council (EPSRC) via the Early Career Fellowship EP/R001642/1. The authors are grateful with Vicky Leadley and Leslie Arkless for assistance with NMR measurements, and Dan Geddes from the University of Sheffield for assistance with MIP measurements. The data associated with this paper are openly available from the University of Leeds Data Repository, at https://doi.org/10.5518/1227.
Copyright © 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
- Blast furnace slag
- alkali-activated cements
- hybrid cements
- reaction kinetics