Heterogeneous nucleation of ice from supercooled NaCl solution confined in porous cement paste

• Pore structures of the HCP samples were characterized.
• Strong heterogeneous ice nucleation of NaCl solution were reported.
• Increasing NaCl concentration decreases median nucleation temperature.
• The contact angle between ice and the HCP substrate is the minimum at 3% NaCl.
• Heterogeneous ice nucleation rates increase linearly as water activity shifts increase.

Clarifying the nucleation process of chloride-based deicing salt solution (e.g., NaCl solution) confined in cement-based porous materials remains an important issue to understand its detrimental effects on material substrates. In this study, the pore structures of hardened cement pastes were characterized by mercury-intrusion and nitrogen-sorption porosimetry. The ice nucleation temperature of NaCl solution of different concentrations confined in the hardened cement pastes was measured and analyzed by classical heterogeneous nucleation theory. The kinetic factor, contact-angle factor including the contact angle between ice and the substrate were evaluated. The results revealed that the contact angle between ice and the substrate showed the minimum value when adding 3% NaCl into water. The heterogeneous ice nucleation rates were found to be proportional to the water activity shifts.