Wet-gunning method for dense castable refractory composition

The method for wet-gunning a castable refractory composition includes the steps of (a) preparing a cement-free, castable refractory composition comprising 70-98 weight % of refractory aggregate having a particle size of 10 mm or less, 2-30 weight % of ultrafine refractory powder having a particle size of 10 mu m or less, and 0.01-1.0 weight % (outer percentage) of a dispersing agent, and further a thickener (in the case of factory premixing); (b) premixing the cement-free, castable refractory composition with water in situ or in a factory to provide an in-situ premixed or factory-premixed, water-containing refractory material having a castable fluidity; (c) conveying the in-situ premixed or factory-premixed, water-containing refractory material to a gunning nozzle by a pump; (d) adding 0.1-1 weight % (outer percentage) of an alkali silicate or an alkali aluminate as a shape retention agent in the form of an aqueous solution to the in-situ premixed or factory-premixed, water-containing refractory material together with compressed air in the gunning nozzle; and (e) gunning the resulting mixture through the gunning nozzle.