Refractory Technology
Addition of grog in fireclay brick during its manufacture is advantageous, because it results in

Less addition of water to get a workable plasticity & lesser time required for drying the raw refractories and hence increased rate of production
High strength & thermal spalling resistance
All of these
Less shrinkage in heating, decreased apparent porosity & increased specific gravity

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Refractory Technology
Magnesite chrome refractories

Have very low thermal co-efficient of expansion
Have better spalling resistance than chrome magnesite refractories
Are not at all resistant to the corrosive action of iron oxide
Have very low (50 kg/cm² ) cold crushing strength (C.C.S.), and can not be used in metalcase form

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