Microstructural and Phase Characteristics of Phosphogypsum-Cement Mixtures
Publication: Journal of Materials in Civil Engineering
Volume 8, Issue 1
Abstract
The effects of the tricalcium aluminate (C 3 A) content of the stabilizing cement [Type II (1.3% C 3 A) cement and Type III cement (9.3% C 3 A)], curing time (seven to 90 days), proportion of PG (5–60%), grain size, and impurities in phosphogypsum (PG) (PG compared to gypsum) on the microstructural (by scanning electron microscopy) and phase properties of gypsum/PG and cement mixtures, a potential road-base material, were studied (by derivative thermogravimetry). Morphologically, two types of ettringite (well-defined crystals, >2 μm in lengths and ill-defined crystals, below 1 μm in length) were present in the cement and gypsum/PG mixtures. The impurities in PG retarded the initial hydration of cement in direct proportion to its amount in the mixtures. However, gypsum/PG increased the degree of hydration of cement in the mixtures in the long term. The reacted gypsum/PG produced a large amount of ettringite (within two months) compared to cement only. The amount of carbonation was uniformly low.
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Information & Authors
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Published In
Journal of Materials in Civil Engineering
Volume 8 • Issue 1 • February 1996
Pages: 11 - 18
Copyright
Copyright © 1996 American Society of Civil Engineers.
History
Published online: Feb 1, 1996
Published in print: Feb 1996
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