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Title: Effects of Incorporating High-Volume Fly Ash into Tricalcium Silicate on the Degree of Silicate Polymerization and Aluminum Substitution for Silicon in Calcium Silicate Hydrate

Abstract

This study assesses the quantitative effects of incorporating high-volume fly ash (HVFA) into tricalcium silicate (C 3S) paste on the hydration, degree of silicate polymerization, and Al substitution for Si in calcium silicate hydrate (C–S–H). Thermogravimetric analysis and isothermal conduction calorimetry showed that, although the induction period of C 3S hydration was significantly extended, the degree of hydration of C 3S after the deceleration period increased due to HVFA incorporation. Synchrotron-sourced soft X-ray spectromicroscopy further showed that most of the C 3S in the C 3S-HVFA paste was fully hydrated after 28 days of hydration, while that in the pure C 3S paste was not. The chemical shifts of the Si K edge peaks in the near-edge X-ray fine structure of C–S–H in the C 3S-HVFA paste directly indicate that Al substitutes for Si in C–S–H and that the additional silicate provided by the HVFA induces an enhanced degree of silicate polymerization. This new spectromicroscopic approach, supplemented with 27Al and 29Si magic-angle spinning nuclear magnetic resonance spectroscopy and transmission electron microscopy, turned out to be a powerful characterization tool for studying a local atomic binding structure of C–S–H in C 3S-HVFA system and presented results consistent with previous literature.

Authors:
 [1];  [2];  [3];  [4];  [2]
  1. Hanyang Univ., Seoul (Korea)
  2. Univ. of California, Berkeley, CA (United States)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  4. National Univ. of Singapore (Singapore)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1413716
Grant/Contract Number:
AC02-05CH11231
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Materials
Additional Journal Information:
Journal Volume: 10; Journal Issue: 2; Journal ID: ISSN 1996-1944
Publisher:
MDPI
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; calcium silicate hydrate; tricalcium silicate; fly ash; hydration products; X-ray microscopy

Citation Formats

Bae, Sungchul, Taylor, Rae, Kilcoyne, David, Moon, Juhyuk, and Monteiro, Paulo J. M. Effects of Incorporating High-Volume Fly Ash into Tricalcium Silicate on the Degree of Silicate Polymerization and Aluminum Substitution for Silicon in Calcium Silicate Hydrate. United States: N. p., 2017. Web. doi:10.3390/ma10020131.
Bae, Sungchul, Taylor, Rae, Kilcoyne, David, Moon, Juhyuk, & Monteiro, Paulo J. M. Effects of Incorporating High-Volume Fly Ash into Tricalcium Silicate on the Degree of Silicate Polymerization and Aluminum Substitution for Silicon in Calcium Silicate Hydrate. United States. doi:10.3390/ma10020131.
Bae, Sungchul, Taylor, Rae, Kilcoyne, David, Moon, Juhyuk, and Monteiro, Paulo J. M. Sat . "Effects of Incorporating High-Volume Fly Ash into Tricalcium Silicate on the Degree of Silicate Polymerization and Aluminum Substitution for Silicon in Calcium Silicate Hydrate". United States. doi:10.3390/ma10020131. https://www.osti.gov/servlets/purl/1413716.
@article{osti_1413716,
title = {Effects of Incorporating High-Volume Fly Ash into Tricalcium Silicate on the Degree of Silicate Polymerization and Aluminum Substitution for Silicon in Calcium Silicate Hydrate},
author = {Bae, Sungchul and Taylor, Rae and Kilcoyne, David and Moon, Juhyuk and Monteiro, Paulo J. M.},
abstractNote = {This study assesses the quantitative effects of incorporating high-volume fly ash (HVFA) into tricalcium silicate (C3S) paste on the hydration, degree of silicate polymerization, and Al substitution for Si in calcium silicate hydrate (C–S–H). Thermogravimetric analysis and isothermal conduction calorimetry showed that, although the induction period of C3S hydration was significantly extended, the degree of hydration of C3S after the deceleration period increased due to HVFA incorporation. Synchrotron-sourced soft X-ray spectromicroscopy further showed that most of the C3S in the C3S-HVFA paste was fully hydrated after 28 days of hydration, while that in the pure C3S paste was not. The chemical shifts of the Si K edge peaks in the near-edge X-ray fine structure of C–S–H in the C3S-HVFA paste directly indicate that Al substitutes for Si in C–S–H and that the additional silicate provided by the HVFA induces an enhanced degree of silicate polymerization. This new spectromicroscopic approach, supplemented with 27Al and 29Si magic-angle spinning nuclear magnetic resonance spectroscopy and transmission electron microscopy, turned out to be a powerful characterization tool for studying a local atomic binding structure of C–S–H in C3S-HVFA system and presented results consistent with previous literature.},
doi = {10.3390/ma10020131},
journal = {Materials},
number = 2,
volume = 10,
place = {United States},
year = {Sat Feb 04 00:00:00 EST 2017},
month = {Sat Feb 04 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
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  • This study explores the reaction products of alkali-activated Class C fly ash-based aluminosilicate samples by means of high-resolution synchrotron X-ray diffraction (HSXRD), scanning electron microscope (SEM), and compressive strength tests to investigate how the readily available aluminum affects the reaction. Class C fly ash-based aluminosilicate raw materials were prepared by incorporating Na-aluminate into the original fly ashes, then alkali-activated by 10 M NaOH solution. Incorporating Na-aluminate reduced the compressive strength of samples, with the reduction magnitude relatively constant regardless of length of curing period. The HSXRD provides evidence of the co-existence of C-S-H with geopolymeric gels and strongly suggests thatmore » the C-S-H formed in the current system is C-S-H(I). The back-scattered electron images suggest that the C-S-H(I) phase exists as small grains in a finely intermixed form with geopolymeric gels. Despite providing extra source of aluminum, adding Na-aluminate to the mixes did not decrease the Si/Al ratio of the geopolymeric gel.« less
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