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Relaxation characteristics and state evolution of water during the early-age reaction of alkali-activated slag as monitored by low field nuclear magnetic resonance.

Authors :
Cao, Ruilin
Zhang, Zuhua
Zhang, Yamei
Banthia, Nemkumar
Source :
Composites: Part B, Engineering. Aug2022, Vol. 242, pN.PAG-N.PAG. 1p.
Publication Year :
2022

Abstract

Low field nuclear magnetic resonance (LF-NMR) was used to monitor the evolution characteristics of transverse relaxation time (T 2) of the water in sodium hydroxide (SH) and sodium silicate (SS) activated slag pastes. According to the T 2 weighted average value evolution curve, the early-age reaction process of SH-activated system could be divided into three typical stages: initial setting stage (I), acceleration stage (II) and deceleration stage (III). However, another two distinguishable stages including the second acceleration stage (Ⅳ) and the second deceleration stage (Ⅴ) could be identified in SS-activated system. The essential reactions in different reaction stages of the two types of alkali-activated pastes were discussed. The obtained relaxation signals were employed to determine the chemically bound water content in different alkali-activated slag (AAS) pastes at specific reaction stages, as well as the dynamic change of the relative contents of gel water, capillary water and free water with reaction time. The influence mechanism of the initial active SiO 4 4− oligomer in activator solution on the early-age reaction of AAS was revealed. A distinct water release behavior was observed in the geopolymerization process at the acceleration stages of each AAS paste. • The T 2 evolution characteristic of water in AAS pastes is monitored by LF-NMR. • The chemically bound water content at specific reaction stages is calculated. • The evolution of relative content of gel water, capillary water and free water is revealed. • A water release behavior is observed during the reaction process of AAS pastes. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
13598368
Volume :
242
Database :
Academic Search Index
Journal :
Composites: Part B, Engineering
Publication Type :
Academic Journal
Accession number :
158332027
Full Text :
https://doi.org/10.1016/j.compositesb.2022.110025