Characterizing two types of zonation within slag rims of aged alkali-activated slag pastes through SEM and TEM

Journal article (2023)

Authors

Y. Zhang Southeast University, Materials and Environment - CEG
Shizhe Zhang Renewi Mineralz & Water, Materials and Environment - CEG
C. Liu Materials and Environment - CEG
Oguzhan Copuroglu Materials and Environment - CEG
Research Group
Materials and Environment (CEG) (TU Delft)
Copyright: © 2023 Y. Zhang, Shizhe Zhang, C. Liu, Oguzhan Copuroglu
DOI: https://doi.org/10.1016/j.cemconres.2023.107409
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Published Date

2023

Language

English

Faculty

Civil Engineering & Geosciences

Department

Materials- Mechanics- Management & Design

Research Group

Materials and Environment

Abstract

In this paper, the authors characterized two types of zonation within slag rims in aged alkali-activated slag (AAS) systems through SEM and TEM technology. These two elemental zonation were closely related to the pore structure of AAS pastes, thus providing strong implication for the transport- and durability-related performance of AAS systems. The first type of zonation occurred in the rims of AAS specimens under sealed curing. It was found that lath-like hydrotalcite-like phase accumulated near the boundary while a generally homogeneous and foil-like C-(N-)A-S-H gel phases precipitated in the following sub-zone. When slag rims were thick enough, a new Mg-rich region occurred. The second type of zonation was noticed in the carbonated AAS pastes. For this kind of distribution pattern, C-(N-)A-S-H gel phases were observed near the boundary. Following, the accumulation of Mg and Ca occurred alternatively. Additionally, transformation mechanism between these two types of zonation was also proposed.