Engineering tool
Apparent Porosity & Bulk Density Calculator
Calculate apparent porosity, bulk density, water absorption and apparent specific gravity of a refractory by the Archimedes method, from dry, saturated and suspended weights.
Apparent porosity — %
Bulk density — g/cm³
Water absorption — %
Apparent specific gravity —
Enter all weights in grams. Valid input requires W ≥ D and W > S. Water density is taken as 1 g/cm³.
Formulas used
- Apparent porosity % = ((W − D) ÷ (W − S)) × 100
- Bulk density = D ÷ (W − S) × ρ_water
- Water absorption % = ((W − D) ÷ D) × 100
- Apparent specific gravity = D ÷ (D − S)
Practical notes
- The method rests on the Archimedes principle: the sample is dried, then saturated with water, then weighed while suspended in water.
- Weighing accuracy propagates straight into the result — the difference W − S is small, so an error there matters more than it looks.
Frequently asked questions
What does apparent porosity tell me?
The percentage of open pore volume relative to total sample volume. It is the key indicator of permeability, corrosion resistance and firing quality in a refractory.
How do bulk density and apparent specific gravity differ?
Bulk density is mass per unit volume including open pores. Apparent specific gravity considers only the solid part, so it is independent of porosity.