Investigation on the structure of fully hydrated portland cement and tricalcium silicate pastes. III. Specific surface area and permeability

On a series of d-dried OPC pastes hydrated at 20 and 90 °C and Ca₃SiO₅ pastes hydrated at 20 °C the specific surface area was measured using four different methods i.e. BET_{N 2} and those calculated from adsorption isotherms and BET_{H 2 0} mercury porosimetry and water permeability data. Values found using different methods were not identical. In addition to that, the specific surface area of the same pastes in non-dried state was estimated from their permeability to water. A drying and resaturation of the pastes resulted in a decrease of the specific surface area indicating a coarsening of the pore structure in the course of drying.