Microstructural and compositional change of NaOH-activated high calcium fly ash by incorporating Na-aluminate and co-existence of geopolymeric gel and C-S-H(I)

Journal Article · Tue May 15 00:00:00 EDT 2012 · Cement and Concrete Research

DOI:https://doi.org/10.1016/j.cemconres.2012.02.002· OSTI ID:21596966

Oh, Jae Eun ^[1]; Moon, Juhyuk ^[1]; Oh, Sang-Gyun ^[2]; Clark, Simon M ^[3]

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1. Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720 (United States)
2. Department of Architectural Engineering, Dong-Eui University, 995 Eomgwangro, Busanjin-Gu, Busan 614-714 (Korea, Republic of)
3. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 20015 (United States)

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 that 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.

• OSTI ID: 21596966
• Journal Information: Cement and Concrete Research, Journal Name: Cement and Concrete Research Journal Issue: 5 Vol. 42; ISSN 0008-8846; ISSN CCNRAI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AEROSOL WASTES
ALKALI METAL COMPOUNDS
ALKALINE EARTH METALS
ALUMINATES
ALUMINIUM
ALUMINIUM COMPOUNDS
ASHES
BUILDING MATERIALS
CALCIUM
CEMENTS
COHERENT SCATTERING
COLLOIDS
COMBUSTION PRODUCTS
COMPRESSION STRENGTH
CURING
DIFFRACTION
DISPERSIONS
ELECTRON MICROSCOPY
ELEMENTS
FLY ASH
GELS
HYDROGEN COMPOUNDS
HYDROXIDES
IMAGES
MATERIALS
MECHANICAL PROPERTIES
METALS
MICROSCOPY
MICROSTRUCTURE
OXYGEN COMPOUNDS
RAW MATERIALS
RESIDUES
SCANNING ELECTRON MICROSCOPY
SCATTERING
SODIUM COMPOUNDS
SODIUM HYDROXIDES
WASTES
X-RAY DIFFRACTION