People literally understand unshaped refractory materials, that is, refractory products that do not have a fixed shape like standard brick refractory bricks. There is no clear distinction between shape and type in a typed or literal sense. Common unshaped refractory materials are: castables, refractory mud, refractory cement, refractory soil, etc. What they all have in common is that they are all powdered and have no fixed shape. They can be applied to the surface of the kiln, where it can fill gaps in the masonry.