Influence of Seawater Curing in Standard and High-Strength Submerged Concrete

The construction of some maritime structures (e.g., reinforced concrete caissons) is cheaper and easier when made on floating docks. In this case, concrete is submerged just hours after casting, is cured in contact with seawater and remains submerged for its whole service life. Most international standards do not allow this type of curing for reinforced concrete, although there are not many experimental results on its final effects on concrete properties. A research program has been developed to determine the effect of seawater curing on reinforced concrete properties. Different tests (density, compressive strength, porosity, absorption, capillarity and chloride penetration rate) have been carried out on different quality concretes, cured with tap water or seawater. The results show that differences are found in concrete properties in the short term in seawater-cured concretes, but these differences dissipate at later stages for standard quality submerged concretes [water-cement ratio $(\mathrm{w}/\mathrm{c})=0.45$]. Small differences remain for high-quality concretes ($\mathrm{w}/\mathrm{c}=0.40$ and silica fume admixture), where chlorides penetrate deep inside, attributable to seawater curing (7 mm for ordinary portland cement and 6 mm for silica fume concretes, approximately).