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Diatomaceous Earth as a Pozzolan in the Fabrication of an Alkali‐Activated Fine‐Aggregate Limestone Concrete
Author(s) -
Miller Sean A.,
Sakulich Aaron R.,
Barsoum Michel W.,
Jud Sierra Eva
Publication year - 2010
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.1551-2916.2010.03788.x
Subject(s) - lime , portlandite , compressive strength , pozzolan , curing (chemistry) , thermogravimetric analysis , materials science , alkali–aggregate reaction , calcination , efflorescence , fourier transform infrared spectroscopy , aggregate (composite) , composite material , alkali metal , mineralogy , cement , chemistry , chemical engineering , metallurgy , portland cement , organic chemistry , engineering , catalysis
Two concretes—with Ca/Si ratios of 0.28 and 1.75 fabricated by cementing a fine‐limestone aggregate with a mixture of lime, diatomaceous earth, and water—were compared with ones made with pure lime and a hydraulic lime product, containing ∼11 wt% naturally occurring reactive silica. When the Ca/Si ratio in the cementing phase was 0.28, compressive strengths of ∼6.5 MPa after 30 days and ∼7 MPa after 180 days were achieved by curing the samples in closed containers or in 100% relative humidity. When allowed to dry, however, these samples lost roughly half their compressive strength in 7 days. Increasing the Ca/Si ratio to 1.75 solved the drying problems. The resulting compressive strengths, however, after 180 days, were reduced to 5 MPa. Characterization of the various cementing phases formed in the different samples by X‐ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis showed the formation of two, somewhat competing, cementing reactions: C–S–H gel formation which results in early strength gains, and the recarbonation of portlandite, which results in longer term strength enhancements.