A geometrical fractal model for the porosity and permeability of hydraulic cement pastes

This study reports on a geometric model which capably represents various aspects of the porosity of hardened cement pastes. It is composed of two interconnected fractal units. The experimental data for model development and appraisal is obtained from the cumulative curve of mercury intrusion porosimetry on pastes of Type I Portland Cement (water/cement: 0.3–0.7; curing ages: 1–56 d). The fractal character of the porosity was recorded to 2–3 orders of magnitude of the pore size, between about 2 nm and 1 μm. On a par with the fractal dimension, the predictions of the model are in agreement with the experimental data even with regard to the fraction of the voids and the range and distribution of pore size. Finally the model has been used to calculate fluid permeability coefficients which are in accord with the experimental values.