Influence of Accelerating Admixtures on the Reactivity of Synthetic Aluminosilicate Glasses

This research aims at gaining a further understanding of the impact of accelerating admixtures on the reactivity of supplementary cementitious materials (SCMs), which are widely used as a clinker replacement in blended cements. This was done on synthetic glasses with controlled composition and struc...

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Bibliographic Details
Published in:Materials 2022-01, Vol.15 (3), p.818
Main Authors: Gonzalez-Panicello, Laura, Garcia-Lodeiro, Ines, Puertas, Francisca, Palacios, Marta
Format: Article
Language:English
Subjects:
Accelerating agents
Admixtures
Aluminosilicates
Aluminum
Aluminum silicates
Cement
Cements
Clinker
Composition
Dissolution
Enthalpy
Ethanol
Experiments
Fly ash
Glass
Hydration
Mechanical properties
Pastes
Polymerization
Reaction products
Reactivity
Slag
Sodium
Sodium hydroxide
Sodium thiocyanate
Sodium thiosulfate
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Summary:This research aims at gaining a further understanding of the impact of accelerating admixtures on the reactivity of supplementary cementitious materials (SCMs), which are widely used as a clinker replacement in blended cements. This was done on synthetic glasses with controlled composition and structure that mimic two types of real SCMs (slag and calcium-rich fly ash). The effects of DEIPA, TIPA, NaSCN and Na S O on the glass dissolution, hydration kinetics and reaction products were investigated. The obtained results concluded that the pH of the NaOH solution and the composition of the synthetic glass play a key role on the effect of the admixtures. In 0.1 M NaOH (pH = 13.0), all the studied admixtures inhibited the dissolution of slag-like glasses while they enhanced the dissolution of Ca-rich fly ash-like glasses, being Na S O the admixture that led to the highest increase of the dissolution rate of the Ca-rich fly ash-type glasses. In 1 M NaOH solutions (pH = 13.8), only the alkali admixtures (NaSCN and Na S O ) enhanced the degree of reaction of both glasses. In slag-type glasses pastes mixed with 1 M NaOH, the addition of 2% Na S O induced the highest increase of their reactivity as inferred by the total heat release and the amount of bound water. This is related to the formation of a high amount of S(II)-AFm, in addition to C-A-S-H, that would increase the aluminium undersaturation of the pore solution and consequently the further dissolution of the glass.
ISSN:1996-1944
1996-1944
DOI:10.3390/ma15030818