THERMAL-SHOCK AND SIZE EFFECTS IN CASTABLE REFRACTORIES

To study accurately the effects of thermal shock on castable refractor ies, it is necessary to model the fracture profess zone. The fictitiou s crack model, which is often used for the analysis of cementitious ma terials, is a suitable way to include the fracture process zone in the rmal shock analysis. The analysis reinforces the importance of the the rmal shock resistance parameter, R'''', which has the units of length and is very similar to the characteristic length, l(ch), used as a siz e scale in studies of the fracture of cementitious materials. Whether a cementitious bar behaves in a brittle or ductile fashion depends on the size of the bar relative to its characteristic length. Therefore, the behavior of refractories after they have been quenched is dependen t on their size relative to R''''. It is also shown that the critical temperature to cause strength degradation by thermal shock is dependen t on the relative size of the bar.