Six-Year-Old Ecological Concrete in a Marine Environment: A Case Study

The durability of ecological concrete in a marine environment is of concern for the coastal and offshore construction industry. The properties of such concrete taken from a marine structure were studied. Specimens of six-year-old submerged ecological concrete were taken from a breakwater located in the East Mediterranean Sea. The specimens were analyzed for their biological carbonate deposition cover, chloride effective diffusion, carbonation, compressive strength, and mineralogy. About 57% of the surface was found to be covered by biogenic-deposited carbonates. The effective chloride diffusion coefficient and the carbonation rate were found to be reduced proportionally to the biogenic-carbonate cover, relative to the prediction by a standard model. No significant change in compressive strength was detected. Most of the aluminates were found in non-crystalline minerals. No evidence of a sulfate attack was found. In conclusion, the effect of the biological growth on the concrete surface is mainly a reduction of effective diffusion, and no negative effects were detected.