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The refractories used at temperatures up to 1400~ in continuous heating furnaces of rolling mills are subjected to the influence of scale and to that of water vapor when the scale is flushed off the furnace hearth with water; they also undergo thermal shock during charging and discharging of the ingots and suffer mechanical damage when the latter are ejected [I, 2].The walls and roofs of continuous heating furnaces are largely made from aluminosilicate refractories.Petrographic analysis of chamotte roof refractories after service revealed that in the working zones of the refractories there is a marked increase in the content of vitreous substance and acicular mullite grains; isometric mullite grains appear and the number of pores increases.Thermal shocks induce principally wear of the roof refractories by spalling.The most intense wear is exhibited by the roofs of the high-temperature (weld) zones of the furnaces: The spelling length ranges from 10 to 70 mm. In most cases the roof brickwork in these zones does not last for more than 1 year. At certain points in the high-temperature zones (particularly at the junction with the roof) the wall brickwork after service is covered with cracks. In the low-temperature (continuous) zones of the furnaces, after service for 2-3 years the refractories display far fewer spallings and cracks than the hightemperature zones; in general they have been scorified by a thin layer of scale.We have investigated various compositions of guniting masses for repairing the lining of high-temperature (weld) and low-temperature (continuous) zones of heating furnaces. For these investigations we used aluminosilicate and magnesite--chromite (chrome--magnesite) powders. As chemical binders we tried the following hydraulic binders: alumina cement meeting the requirements of All-Union State Standard (GOST) 969-66; high-alumina cement of the aluminothermal industry, meeting the requirements of Technical Specification (TU) 21-20-9--73; and the following binder--humidifiers: magnesium and aluminum sulfates MgSQ. 7H20 and A12(SO4)3, sodium water glass (density 1.2 g/cm3), commercial sodium polyphosphate (NaPO3)20_22 with mean degree of polymerization 20-22, water, and a sulfate--clay binder obtained by dispersion of 107o* of finely ground refractory clay in a 30-40~ aqueous solution of magnesium sulfate [3]. * Here and below the fractions by weight are given.

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