It is found that the casting rejections recycled hinder fluidization due to the presence of gypsum contamination arising out of plaster moulds which acts as the source of Ca2+ and SO42- ions. SO42- ions promotes flocculation. They also induce thixotropy in the slip which reduces casting time. But the cast is of flabby nature due to higher water content. The structure of the cast formed on the plaster moulds depends on the choice of defocculant.
Drying shrinkage and cracking tendency is not dependent on the water content of the slip. It is dependent on the water content of the cast piece. The thickness of the cost increases proportionally to the square root of casting time.
To be contd…….
