According to Weibull’s model, strength of material varies with the volume of the material tested. To experimentally investigate the volume dependence of strength for monolithic refractories, small size 3-point bending tests and large size 4-point bending tests were conducted. The material strength of the large size 4-point bending test was estimated from the bending strength and Weibull modulus obtained from the small size 3-point bending test, and compared with the bending strength of the large size 4-point bending test obtained in the actual test, the deviations are slightly larger. To investigate the cause of the deviations, the maximum stress σx determined by the stress analysis of bending test specimen on the loading was lower than the bending strength for the case of 3-point bending, but higher than that for the case of 4-point bending. The deviation could be decreased considerably correcting the errors included in the calculation of bending strength by based on the assumption of an elementary beam theory. In the analysis of cracking due to drying shrinkage in the refractory lining of a tundish, the cracking seemed much severer the refractory materials with high Weibull modulus larger cracks in the inner lining with a fracture model taking into account the volume dependence of strength.

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