Hydration characteristics of tetracalcium aluminoferrite phase in mixes containing beta-hemihydate and phosphogypsum

Tetracalcium aluminoferrite phase was prepared from pure chemicals on a laboratory scale. Five mixes were prepared from the prepared C(4)AF phase, beta-hemihydate, phosphogypsum and calcium hydroxide. The mixes were hydrated at various intervals namely, 24, 72, 168 and 336 h. The kinetics of hydration was mentioned by measuring the chemically combined water and combined lime contents. The phase composition and microstructure were studied by FT-IR Spectroscopy, XRD, DTA and SEM techniques. This work aimed to study the effect of partial to fully substitution of beta-hemihydrate for phosphogypsum on the hydration characteristics and microstructures of tetracalcium aluminoferrite phase. The mechanism of the hydration of tetracalcium aluminoferrite phase in the presence of phosphogypsum proceeds through a similar manner as in the case of beta-hemihydrate and affects to a slight extent the rate of hydration reaction. (C) 2003 Kluwer Academic Publishers.