Capillary Rise in Granitic Rocks: Interpretation of Kinetics on the Basis of Pore Structure

Area of Science:

• Geology and Materials Science
• Porous Media Physics
• Hydrogeology

Background:

• Capillary transport of water in granitic rocks is crucial for understanding moisture movement and weathering.
• The porous network structure, particularly fissure sizes, significantly influences water infiltration and retention.
• Previous models often simplified the complex pore geometry of granitic rocks.

Purpose of the Study:

• To interpret capillary water transport in granitic rocks based on their porous network structure.
• To calculate an effective pore radius using a modified single-pore model.
• To establish a relationship between pore structure characteristics and moisture capillary rise rates.

Main Methods:

• Utilized a three-sized single-pore model proposed by Dullien, El-Sayed, and Batra.
• Characterized granite's porous network as comprising macro- and microfissures.
• Calculated an effective pore radius based on characteristic radii of macro- and microfissures.

Main Results:

• An effective pore radius was successfully calculated, showing good agreement with experimentally measured capillary rise rates.
• The study demonstrated that predicting capillary transport rates is possible using only two characteristic pore sizes (macro- and microfissure radii).
• An abnormally low capillary rise rate in one granite sample was explained by the exclusive involvement of macrofissures in water transport.

Conclusions:

• The proposed model effectively links granitic rock pore structure to capillary water transport phenomena.
• Characteristic fissure sizes are key parameters for predicting water movement in granites.
• Understanding pore network heterogeneity is essential for accurate hydrogeological assessments of granitic formations.