TY - JOUR
T1 - Comparative Analysis of the Influence of Sodium and Potassium Silicate Solutions on the Kinetics and Products of Slag Activation
AU - Dakhane, Akash
AU - Peng, Zihui
AU - Marzke, Robert F
AU - Neithalath, Narayanan
N1 - Funding Information:
The writers gratefully acknowledge Holcim US and PQ Corporation for providing the materials used in this study. The work was carried out in the Laboratory for the Science and Sustainable Infrastructural Materials (LS-SIM) and the Physics NMR facility at Arizona State University, and the support that has made the establishment and operation of these laboratories are also acknowledged
Publisher Copyright:
Copyright © 2014 by ASTM International.
PY - 2014/12/31
Y1 - 2014/12/31
N2 - This paper primarily explores the influence of the alkali cation (Na or K) on the reaction kinetics, product formation, gel structure, and mechanical properties of alkali activated slag systems. For the same activator Ms, i.e., molar SiO2-M2O ratio (M=Na or K), a shorter induction period, a larger acceleration peak, and consequently, a higher amount of total heat release under isothermal conditions is observed for the K-silicate activated slag pastes. The early-age compressive strengths in these systems roughly relate to the heat release response. The later-age (7 days and beyond) compressive strengths are observed to be higher for the Na-silicate activated systems, which is corroborated by: (1) higher amounts of C-(A)-S-H gel in this system indicated by a thermal analysis-based approximate quantification method, and (2) higher combined intensities of Q1 and Q2 structures that point to increased degrees of reaction, and lower amounts of unreacted slag obtained from 29Si magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. The NMR spectra also show evidences of Al-substituted C-S-H gel, with a higher amount of substitution when Na-silicates are used.
AB - This paper primarily explores the influence of the alkali cation (Na or K) on the reaction kinetics, product formation, gel structure, and mechanical properties of alkali activated slag systems. For the same activator Ms, i.e., molar SiO2-M2O ratio (M=Na or K), a shorter induction period, a larger acceleration peak, and consequently, a higher amount of total heat release under isothermal conditions is observed for the K-silicate activated slag pastes. The early-age compressive strengths in these systems roughly relate to the heat release response. The later-age (7 days and beyond) compressive strengths are observed to be higher for the Na-silicate activated systems, which is corroborated by: (1) higher amounts of C-(A)-S-H gel in this system indicated by a thermal analysis-based approximate quantification method, and (2) higher combined intensities of Q1 and Q2 structures that point to increased degrees of reaction, and lower amounts of unreacted slag obtained from 29Si magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. The NMR spectra also show evidences of Al-substituted C-S-H gel, with a higher amount of substitution when Na-silicates are used.
KW - alkali activation
KW - cationic type
KW - isothermal calorimetry
KW - NMR spectroscopy
KW - slag
KW - thermal analysis
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U2 - 10.1520/ACEM20140005
DO - 10.1520/ACEM20140005
M3 - Article
AN - SCOPUS:84953419182
SN - 2379-1357
VL - 3
SP - 371
EP - 387
JO - Advances in Civil Engineering Materials
JF - Advances in Civil Engineering Materials
IS - 1
ER -