Conference, Proceedings

44
Realative pore volume (%)
100
10
1
1,E +00 1,E +01 1,E +02 1,E +03 1,E +04 1,E +05 1,E +06
Pore radius (nm)
Figure 1: Pore size distribution curve in double logarithmic representation for calcium silicate
For the calcium silicate board with bulk density of 250 kg/m3 the relative pressure‐volume data
were determined by the 2002 mercury intrusion porosimeter and the micropore unit 120 of
ERBA Science, enabling the determination of pores with radii from 3.7 nm up to 0.06 mm. The
pore size distribution was determined from the volume intruded at each pressure increment.
Total porosity was determined from the total volume intruded. The specific surface area of
pores was calculated from the pore radii and the pore volumes. The obtained cumulative pore
size distribution curve for calcium silicate is in figure 1.
The pore volume ‐ pore size distribution curve in a double logarithmic representation can be
divided into the pore space fractions characterized by a constant slope and indicating the ranges
of self‐similarity. The slope of each fraction gives the fractal dimension FD of the pores in the
fraction.
The mean fractal dimension of a relevant pore volume consisting of i fractions is calculated
according to the relationship:
∑ FDi
⋅log(
rmax
i / rmin
i )
i FDm
=
log(
rmax
/ rmin
)
(2)
where rmaxi, rmini are the maximum and minimum pore radii of particular fractions, rmax,
rmin are maximum and minimum pore radii of the relevant volume.
3 Transport parameters model
Generally the effective transport parameter can be expressed by a power function model in
which the transport parameter Ki of the ith continuous material component (solid, gaseous,
liquid) contributing mostly to the transport can be approximated according to the relation [4]: