Refractory Properties - Porosity

In refractories, porosity is reported as "% apparent porosity". Apparent porosity refers to the pores (or voids) connected to the surface, or open pores. The open pores directly affect properties such as slag resistance and permeability.

Generally, refractories with a high amount of porosity have excellent insulating properties but low density, corrosion resistance, and strength. Lower porosity improves strength, load bearing capacity and corrosion resistance (via less slag penetration) but can lower thermal shock resistance. In more porous brick, the pores present act as crack inhibitors. As a result, the amount of porosity is a compromise that you must weigh, depending on the specific service condition.