Bulk Density of Refractory Samples

19-July-2020

Bulk Density of Refractories

This property is important for both insulating and dense refractories (shaped and unshaped). Bulk density (B.D.) is the ratio of the mass of the refractory specimen to the bulk volume of the same or in other words it is the weight per unit volume the refractory (including the volume of the pore space present in that refractory sample).

There are two methods for determination of Bulk Density in case of refractories:

1. Direct measurement method

B.D.= (Weight of the specimen in gm.) ÷ (Volume of the specimen in cc)

2. Direct volume determination method

B.D (gm/cc) = (Dry weight) ÷ (Soaked weight - Suspended weight)

Related Article: Green BD (Bulk Density), Burned BD and Moisture Content of Green Mixture (Powder) of Alumina Refractory Bricks

Fig: Refractory Shapes (PCPF)

Out of these two methods the ‘direct volume determination method’, which is generally used for irregular refractories, gives more accurate results. The nearer the Bulk density approaches the Specific Gravity the lower is the Porosity. Lower B.D indicates higher porosity, lower strength of the refractory material. The BD will also affect other properties of the refractory such as the load bearing capacity and thermal conductivity etc. Unless there is any specific reason, the aim of a refractory manufacturer is to produce products of higher Bulk Density. The ultimate Bulk Density of the product will depend on a number of factors like - type of raw materials used and their processing, process control at every step during green manufacturing and firing etc.