also called open porosity. the percentage of the volume of open pores in refractory products to the total volume of the product. unless otherwise specified, the porosity referred to in the chinese refractory industry usually refers to apparent porosity. apparent porosity is an important indicator for evaluating the quality of refractory raw materials or products. it not only reflects the density of refractory materials, but also indicates whether its manufacturing process is reasonable. in addition to lightweight refractory products, low porosity raw materials or products are beneficial to improving product quality, improving the mechanical strength of the product, reducing the surface area in contact with slag, and extending the service life.

apparent porosity formula:

apparent porosity = ( s - w / s - i ) * 100

s - weight of piece soaked

w - weight of dry piece

i - weight of the piece soaked and immersed.