1- The effect of using sea water on concrete:

Exposure to sea water can lead to the deterioration of concrete through processes like chloride ingress and sulfate attack. Chloride ions penetrate the concrete, reaching the reinforcing steel and causing corrosion, which can result in structural damage.

2- The ways to protect concrete from seawater:

To protect concrete from seawater, several methods are employed:

- High-Quality Concrete Mix:

Using a mix with low permeability reduces the risk of chloride penetration.

- Admixtures:

Adding corrosion inhibitors or air-entraining agents can enhance concrete durability in aggressive environments.

- Surface Coatings:

Applying protective coatings like epoxy or urethane can create a barrier against chloride penetration.

- Cathodic Protection:

This electrochemical method helps prevent steel corrosion by supplying a protective current to the reinforcing steel.

- Use of Corrosion-Resistant Reinforcement:

Employing stainless steel or epoxy-coated reinforcement bars enhances corrosion resistance.

Reference:

• Neville, A. M. (2011). Properties of Concrete. Pearson.
• Mindess, S., Young, J. F., & Darwin, D. (2003). Concrete. Prentice Hall.

Seawater should never be used to mix concrete for reinforced structures. Chloride ions reduce the natural basic ph of concrete and therefore cause corrosion of steel reinforcement.

Sea water was used in the past in some regions because the salt (NaCl) increases the speed of the hydration reaction of concrete. Today's experience has demonstrated that it was a terrible mistake.