RHEOLOGICAL PROPERTIES OF MULTIPHASE PLASTERS

The effects of formulation constituents and the working temperature on the rheological properties of gypsum mortars made from natural and FG D (flue gas desulpho) gypsums were investigated systematically using e xperimental design methods. Rotation and oscillation rheometry and a s pecial method for simulating the power used when smoothing gypsum mort ars were compared with one another as the rheological test methods. Fo r this last method a special laboratory device was developed which was submitted to a practical test by contrasting the measured results wit h an assessment of the workability properties by plasterers using the same gypsum mortar. It was found that natural gypsum and FGD gypsum pl asters give substantially the same properties when used as components of formulated multiphase plasters. In many cases the formulation param eters and the temperature have joint effects and therefore cannot be c onsidered in isolation. The rheological measuring methods together wit h the statistical test design form a tool with which it is possible to optimize the formulation of premixed multiphase plasters and machine- applied plasters.