This International Standard specifies two methods for the determination of the bulk density of granular refractory materials (grain density) having a grain size larger than 2 mm : — Method 1 : the mercury method with vacuum — Method 2 : the arrested water absorption method. Method 1 is intended as the referee method. Depending on the nature of the material tested, the two methods may give different results. Any statement of the value of a bulk density shall therefore be accompanied by an indication of the method used or to be used in case of dispute. The same method shall be used for the determination of the volume of the sample, for selecting and preparing the sample, for calculating the bulk density and for presenting the test report.