Real density

Is defined as the ratio of the dry specimen mass to the volume of its solid part. It is therefore measured in kg/m3. For dense, low porosity stones the differences between real and apparent density are very small; for these stones it is sufficient to determine the apparent density; in other cases the real density should be also determined (EN 1936).
For this test, after the determination of apparent density and open porosity, each specimen is separately grounded to powder size and dried. About 20 g of the powder are weighed (me) and introduced into a pycnometer half full of water. Then the pycnometer is filled with deionised water and weighed (mi). Finally the pycnometer is emptied and washed, filled with deionised water only and weighed (m2). The real density (ρr) is expressed as the ratio of the mass of the ground dry specimen me to the volume of liquid displaced by this mass, by the following equation:
ρb = (me /m2+ me -m1)* ρw (kglm3)
me is the mass of the ground dry specimen (g)
ml is the mass of the pycnometer containing the ground dry specimen and water (g)
m2 is the mass of the pycnometer full of water (g)
ρw is the density of water (kg/m3)