Testing Methods for Refractory Plastics and Ramming Mixes

Refractory plastics and ramming mixes are unshaped refractories installed by tamping or ramming. Because of differences in their binders, their plasticity and workability differ. When the plasticity index is greater than 15 the material is called a plastic; below 15 it is a ramming mix. Dry vibratable mixes have no plasticity but are usually also installed by ramming. Apart from how specimens are formed, the testing methods for plastics and ramming mixes are essentially the same as for castables.

For refractory plastics and ramming mixes, Chinese laboratories generally form specimens by hand ramming or with a compression testing machine. In Germany, an automatic rammer with a pneumatic hammer is used while the mould moves back and forth at a uniform speed, compacting the material layer by layer. US standards prepare specimens by press forming.