Physicochemical Properties of Portland Cement/Calcium Aluminate Cement/Calcium Sulfate Ternary Binder Exposed to Deep Seafloor

Cementitious materials employed in deep‐sea marine engineering must have excellent durability. In this study, the durability of a ternary binder‐based paste composed of Portland cement, calcium aluminate cement, and anhydrite was investigated after deep‐sea exposure at a depth of 3515 m for 438 days. The recovered paste specimen showed significant expansion. However, the hydrate phases in the ternary binder exhibited no changes with the exception of the formation of Friedel's and Kuzel's salts. One reason for this was the transformation from unstable monosulfate to stable ettringite under low‐temperature seawater conditions. However, the additional ettringite formation could lead to significant expansion of the paste specimen.