Rheology calcium aluminate cements

The rheology of calcium aluminate cement pastes is broadly similar to that of Portland cement pastes (Banfill and Gill, 1986). They show a Bingham-type behavior with slightly lower yield values and a plastic viscosity. If agitated, they exhibit a stmctural breakdown that depends on the intensity and duration of mixing. Their flow curves are characterized by a distinct hysteresis loop. Usually, concrete mixes made with calcium aluminate cement are somewhat more free flowing, which makes it possible to use a lower water/cement ratio. 

Hasegawa et al (1995) developed a new cementitious material by combining calcium aluminate cement with a methanolic solution of a phenol resin precursor. The water-free mix must be processed by high-shear mixing in a twin-roller mill in a way similar to that used in the production of MDF materials. The rheology of the resin-cement paste may be improved by adding to the system small amounts of a modifier such as alcohol-soluble polyamide and a plasticizer. A typical mix proportion is as follows ... 

An important constituent of refractory castables that has yet to be considered is the calcium aluminate cement. This raw material is known to strongly affect the dispersion state and rheological behavior of castables due to the various reactions occurring in the material as soon as it comes into contact with the admixing water (43-46). Therefore, an understanding of the effect of additives on the hydration process of cement particles is an essential requirement to optimize the rheological properties and working time of cement-based refractory materials. 

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