This Standard specifies a method based on water absorption with vacuum for the determination of the bulk density of granular refractory materials (grain bulk density) having a grain size larger than 2 mm. NOTE 1: This method is proposed as an alternative to the method based on mercury displacement with vaccum described in EN 993-17 which is to be used as the reference method because of its reproducibility. However, mercury is known to be a hazardous substance and the method described in this EN is recommended for all routine purposes. Nevertheless, depending on the nature of the material tested, the two methods may give different results. NOTE 2: For materi