Characterizations and Quantitative Estimation of Alkali-Activated Binder Paste from Microstructures

Autor: Indrajit Ray, Ben Dawson-Andoh, Arkamitra Kar, Avinash Unnikrishnan, Udaya B. Halabe
Rok vydání: 2014
Předmět:
Zdroj: International Journal of Concrete Structures and Materials. 8:213-228
ISSN: 2234-1315
1976-0485
DOI: 10.1007/s40069-014-0069-0
Popis: Alkali-activated binder (AAB) is recently being considered as a sustainable alternative to portland cement (PC) due to its low carbon dioxide emission and diversion of industrial wastes and by-products such as fly ash and slag from landfills. In order to comprehend the behavior of AAB, detailed knowledge on relations between microstructure and mechanical properties are important. To address the issue, a new approach to characterize hardened pastes of AAB containing fly ash as well as those containing fly ash and slag was adopted using scanning electron microscopy (SEM) and energy dispersive X-ray spectra microanalyses. The volume stoichiometries of the alkali activation reactions were used to estimate the quantities of the sodium aluminosilicate (N–A–S–H) and calcium silicate hydrate (CSH) produced by these reactions. The 3D plots of Si/Al, Na/Al and Ca/Si atom ratios given by the microanalyses were compared with the estimated quantities of CSH(S) to successfully determine the unique chemical compositions of the N–A–S–H and CSH(S) for ten different AAB at three different curing temperatures using a constrained nonlinear least squares optimization formulation by general algebraic modeling system. The results show that the theoretical and experimental quantities of N–A–S–H and CSH(S) were in close agreement with each other. The R2 values were 0.99 for both alkali-activated fly ash and alkali-activated slag binders.
Databáze: OpenAIRE
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