Unshaped refractory compositions useful as jointing and moulding compositions

Claim 1

An unshaped refractory composition which consists essentially of by weight: (a) 55 to 99% of particles of a fused cast refractory material which contains a vitreous phase and the composition of which consists essentially of, as main constituents, ZrO 2 , Al 2 O 3 and SiO 2 , or ZrO 2 , Al 2 O 3 , SiO 2 and Cr 2 O 3 ; (b) 1 to 4% of a hydraulic cement; (c) 1 to 15% of a filler consisting of very fine, substantially spherical particles of a metal oxide selected from the group consisting of vitreous silica, alumina, chromic oxide (Cr 2 O 3 ) and zirconia, the surface area of these particles being higher than 5 m 2 /g; (d) 0 to 25% of fine particles of a size less than 40 microns selected from the group consisting essentially of particles of zirconia, alumina, chromic oxide Cr 2 O 3 , fused cast refractory products the chemical composition of which comprises by weight 75-85% ZrO 2 , 2-8% SiO 2 , 9-17% Al 2 O 3 , 0.5-0.7% of other oxides, and mixtures thereof; the proportion of each of the constituents (a), (b), (c) and (d) being given with respect to the total of the ingredients (a), (b), (c) and (d); and (e) 0.01 to 1% of a surface-active agent, the amount being with respect to the total weight of the constituents (a), (b), (c) and (d), said surface-active agent imparting a Newtonian behavior to the composition.