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Effect of Sodium Silicate on Calcium Aluminate Cement Hydration in Highly Alkaline Media: A Microstructural Characterization
Author(s) -
FernándezJiménez Ana,
Vázquez Tomás,
Palomo Angel
Publication year - 2011
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2010.04242.x
Subject(s) - aluminate , hydrate , calcium silicate hydrate , silicate , sodium silicate , alkali metal , cement , mineralogy , precipitation , chemistry , materials science , compressive strength , fourier transform infrared spectroscopy , nuclear chemistry , inorganic chemistry , chemical engineering , composite material , organic chemistry , engineering , physics , meteorology
The present paper discusses calcium aluminate cement (CAC) hydration in four highly alkaline solutions (8 M NaOH and three sodium silicate solutions with SiO 2 /Na 2 O moduli of 0.19, 0.69, and 1.17). The reference system was water‐hydrated CAC. The hydrated materials were tested for 2‐ and 28‐day compressive and flexural strength and the reaction products were characterized by XRD, fourier transform infrared, and NMR. In highly alkaline media, initial mechanical strength developed much more slowly than in CAC‐water systems. Strength in alkali‐activated CAC rose gradually with time, however, reaching values of approximately 80 MPa in 28‐day specimens, depending on the SiO 2 /Na 2 O ratio in the solution used to hydrate the CAC. The chief conclusion drawn from this study was that hydration proceeds differently in alkaline and neutral media, with C 3 AH 6 precipitating in the former. The addition of sodium silicate to the alkaline hydration solutions used to hydrate the CAC induced the precipitation of katoite [Ca 2 . 93 Al 1.97 (Si 0.64 O 2.56 )(OH) 9.44 ] and an alkaline aluminum silicate hydrate.