|Monthly Tech-Tip |
This measurement is commonly used in evaluating limestone rock, for example. However it can apply to ceramics for aggregate materials. The figure provides some basis to compare the density of the aggregate particles.
Apparent porosity, or the percentage of volume of voids over the total volume of rock can be better understood in context with other related properties:
Bulk density(g/cm3): the weight of the oven-dried rock divided by its total volume (including pore-space), with volume being determined by normal immersion (without the use of a vacuum pump).
Dry density(g/cm3): the weight of the oven-dried rock divided by its total volume, with volume being determined by immersion using a vacuum pump.
Grain density (g/cm3): the weight of oven-dried rock divided by its volume (excluding pore-space).
Water absorption (%): the weight of water absorbed by the rock after 24 hours of immersion in water divided by its oven-dried weight expressed as a percentage of its oven-dried weight.
Effective porosity(%):indicates interconnected pores and is the product of water absorption and bulk density.
Saturation(%): the percentage of pore volume, which can be filled with water after immersion in water for 24 hours.
Apparent porosity (%): the percentage of volume of voids over the total volume of rock. In ceramics this refers to the intrinsic porosity of the mineral particles (or man-made particles e.g. grog or aggregate).