Title: Performance of Typical Protection Methods for Reinforced Concrete in Marine Environment
Author(s): M. Makita, Y. Mori, and K. Katawaki
Publication: Symposium Paper
Appears on pages(s): 453-472
Keywords: accelerated tests; cathodic protection; corrosion resistance; corrosion tests; field tests; marine environments; protective coatings; reinforced concrete; reinforcing steels; zinc coatings.
This report describes laboratory and field tests on the corrosion preventive effects of resin coating, galvanizing, cathodic protection, concrete surface coating and commercial inhibitors used as a protection measures for steel in concrete. The following conclusions were drawn from the test results: (1) The best in protective performance among the epoxy coatings is the powder epoxy. For protective performance, a coating thickness of 150um or greater is required, but for good bond to concrete, the thickness is preferably less than 150um. Thus the coating thickness of 150um is considered to be optimum. The liquid type tar epoxy coating is not satisfactory in its protective performance or for bond to concrete. (2) Galvanization gives good protective performance but is not always satisfactory at the splash zone. (3) Cathodic protection has an excellent protective effect in the tidal area and in seawater. The voltage to be applied is preferably -1000 to -1200mV. When it is higher than -800mV, the effect is not satisfactory, and when lower than -1500 mV, over-protection may result. (4) Urethane coating over the concrete surface failed to give a satisfactory cutoff effect in the tests and proved to be of no protective value. (5) Sodium sulfite series inhibitors had no protective effect.