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

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

Zhang, Y. (TU Delft Materials and Environment; Southeast University)
Zhang, Shizhe (TU Delft Materials and Environment; Renewi Mineralz & Water)
Liu, C. (TU Delft Materials and Environment)
Copuroglu, Oguzhan (TU Delft Materials and Environment)

2023

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.

Alkali-activated slag
Capillary pore
Carbonation
SEM and TEM
Slag rim
Zonation

http://resolver.tudelft.nl/uuid:d19e79cd-83f4-4ca9-8f47-d9b925814d9c

https://doi.org/10.1016/j.cemconres.2023.107409

0008-8846

Cement and Concrete Research, 176

Institutional Repository

journal article

© 2023 Y. Zhang, Shizhe Zhang, C. Liu, Oguzhan Copuroglu