Assessment of the slag and fly ash reactivity in alkali-activated pastes

Conference paper (2018)

Authors

Marija Nedeljković Materials and Environment - CEG
Corrie van Hoek Tata Steel
Stefan Melzer Tata Steel
Sieger van der Laan Tata Steel
G. Ye Materials and Environment - CEG
Research Group
Materials and Environment (CEG) (TU Delft)
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Published Date

2018

Language

English

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Faculty

Civil Engineering & Geosciences

Department

Materials- Mechanics- Management & Design

Research Group

Materials and Environment

Abstract

In this paper, PARC software was used to determine the spatial distribution of the dominant reaction products, their chemical composition and area/volume percentage in alkali-activated fly ash (FA) and ground granulated blast furnace slag (GBFS) pastes. The pastes reacted at different rates and dominant compositional domains were Mg rich gel around GBFS particles, i.e. Ca-(Na-)Al-Si+Mg, while the domains further form the GBFS and FA particles consisted mainly of Ca-(Na-)Al-Si. The reaction degree of GBFS and FA was calculated. Alkali-activated GBFS reacted faster in the studied alkaline conditions, reaching 66 % reaction at 28 days as GBFS contains 99 vol.-% of highly-reactive calcium and magnesium-rich aluminosilicates. The reaction degree in alkali-activated FA and GBFS paste was lower, as FA contains 31 vol.-% of nonreactive phases (quartz, mullite, hematite).
The results obtained from PARC were compared with independent bulk analytical techniques X-ray fluorescence (XRF) and X-ray diffraction (XRD).