In general, Table 1 summarises the comparison of the three methods explained above for the computation of volume fraction of pores (pore volume), organic matter and minerals using the total volume of voxel.
The specific surface area (using BET and BJH methods), the total pore volume and the mean pore diameter were measured using a N2 adsorption desorption isotherm at liquid nitrogen temperature (−196 °C) using a NOVA 2200 instrument (Quantachrome, USA).
The samples appeared to be too small to achieve precise measurements via the Archimedes method; thus, porosity was estimated using a portion of the total pore volume on the SEM images.
The total micropore volume (V micro) was calculated from the N2 adsorption data using the t-plot method, and the total pore volume (V total) was evaluated from the amount of liquid nitrogen adsorbed at P/P 0 of 0.99.
The use of MIP as an indicator of the total pore volume is well-accepted, but its use for pore size determination has several drawbacks (Diamond 2000; Moro and Böhni 2002), primarily because of the presence of "pore-throats" in cement pastes and similar systems.
The pore size distribution was calculated using the desorption curve and the BJH method, and the total pore volume being determined by BJH at the relative partial pressure of p/p 0 = 0.95.
The total pore volume (TPV) of the samples was calculated using the pore size distribution data.
The total pore volumes were evaluated from the adsorption isotherm using the single-point method at a relative pressure of 0.995.
For nitrogen sorption, the total pore volume and pore size distribution were established by using desorption curve, the BET theory, the Harkins Jura t-curve, and the BJH theory.
The total pore volume and pore size distribution were calculated by using desorption curve, the BET theory, the Harkins Jura t-curve, and the BJH theory (Barrett et al. 1951).
