Investigation of Concrete From a Bridge Support after 11 Years of Exposure to Seawater

The concrete bridge structure members, so called skew members (SM), which are positioned from +1.5 m above the sea level to about -20 m down in the sea, and are one of the most important elements in the construction of the bridge, were investigated for maintenance purposes after 11 years of service. The underwater arch foundation concrete was also tested. The compressive strength, determined as the average value of 10 concrete cores drilled-out from each of two skew members - SM-St. Marko and SM-Mainland - was 62.3 MPa and 57.4 MPa respectively. Chlorides had penetrated through the high alkaline composite by over 20 mm in the splash zone concrete and by over 45 mm in the fully submerged concrete where Cl-penetration was probably enhanced by hydrostatic pressure. The lack of corrosion of the steel in the concrete even in the presence of high chloride concentration could be explained by the absence of oxygen. The gas permeability coefficients K (sub g) determined on the concrete cores slices varied in the inner concrete layers of SM-St.Marko from 5.58 to 20.10 x 10 (-13 power) cm (squared) and from 0.55 to 2.84 x 10 (-13 power) cm (squared) in the concrete at SM-Mainland.