Long-term performance of alumina cement concrete mixed with tap water and seawater

A detailed study of concrete specimens (150 mm in diameter and 300 mm in length) made with normal portland cement (NPC) and alumina cement (AL) was carried out after 30 years of exposure to the marine environment. Mixing water was tap water and seawater. Compressive strength, chloride ingress, microstructure, mineralogy, interfaces of concrete, and corrosion of steel bars (electrochemically and physically) were evaluated after 30 years of exposure. AL concrete mixed with seawater shows higher strength compared with the same mixed with tap water. No significant transformation of hydration phases from CAH ₁₀ to C ₃AH ₆ is found for AL concrete mixed with seawater. It shows a dense (almost nonporous) microstructure at the inner and outer regions of the specimens, and also a dense (almost nonporous) steel-concrete interface compared with the same mixed with tap water.