Strength and fracture energy of concrete in seawater

Strength and fracture energy of cement-based materials depend on surface energy of the solid skeleton. Surface energy, however, is influenced by the thickness of adsorbed liquid films and their surface energy. Strength of concrete decreases and the material expands if water is adsorbed on the surface of the nano-structure. This relation can be described adequately by means of the Bangham equation. If concrete is in contact with seawater the surface energy of the solid skeleton is even more reduced than by pure water. In this contribution the influence of seawater on strength and fracture energy has been investigated experimentally. The physical basis of the experimental findings is presented and discussed. Consequences of this phenomenon for the mechanical behavior and in particular for crack formation in concrete structures in contact with seawater or other NaCl-containing water are outlined.