Experimental Study on Anode Life and Effective Distance of Sacrificial Cathodic Protection in Reinforced Concrete

The purposes of this study were to examine influences of concrete quality and environmental severity on anode life and to determine effective distance of sacrificial cathodic protection in reinforced concrete. 100 x 100 x 400 mm3 concrete beams embedded with a reinforcement at distance of 25 mm from top surface were prepared and sacrificial zinc anode plates were attached on top surface of specimens. 700 x 700 x 75 mm3 concrete slabs embedded with reinforcement mesh of 150 mm spacing were prepared and sacrificial anode were attached on top surface of concrete slabs at lower-left corner. The concrete beams and slabs were then exposed to wet-dry cycle and impressed voltage corrosion accelerations. The anode life was determined by time taken for total consumption of anode in concrete beams and the effective distance was determined by distance influenced by polarization effect of sacrificial anode in concrete slabs. Time taken for total consumption of anode and polarization effect were interpreted from corrosion potential data conducted in accordance with the ASTM C876. As a result, the anode life increased with increasing of concrete quality and decreased with increasing of the environmental severity. The effective distance was approximately 500-600 mm from the anode-installed position.

Effect of Conducting Polyaniline/Graphene Nanosheet Content on the Corrosion Behavior of Zinc-Rich Epoxy Primers in 3.5% NaCl Solution

The corrosion behavior of zinc-rich epoxy primers or paints (ZRPs) with different conducting polyaniline-grafted graphene (PANI/Gr) contents was investigated. Conductivity of the formed PANI/Gr nanosheets was significantly improved by employing the Gr as the inner template to synthesize the PANI. The protective properties and electrochemical behavior of coatings with artificial defects were investigated by monitoring the free corrosion potential versus time and by using localized electrochemical impedance spectroscopy (LEIS). A synergetic enhancement of the physical barrier role of the coating and the zinc sacrificial cathodic protection was achieved in the case of ZRP including PANI/Gr nanosheets. In addition, the ZRP mixed with the PANI/Gr at a content of 0.6% exhibited the best anticorrosion performance across the range of investigated PANI/Gr contents.

Corrosion of Aluminum Alloy Used as Sacrificial Anode for Steel Embedded Concrete Transmission Tower in Brackish Mud

This paper presents the cathodic protection of steel embedded concrete of aluminum based alloy in brackish mud. In this experiment, aluminum based alloys containing 5% zinc, 2% magnesium, and 0.5-2% stannum were fabricated. These elements were added because they produce heat treatable alloys, improved anti friction characteristics, fluidibility, and contain highest strengthening effect on aluminum alloys. These alloys were tested as sacrificial cathodic protection for the standard steel embedded concrete exposed to sea water and brackish mud. Surface morphology of the samples after subjected to corrosion was investigated through scanning electron microscopy (SEM) and anode capacity test (efficiency test). The results revealed that sample with the composition of 95.6% of aluminum, 3.83% of zinc, and 0.19% of stannum showed the best performance hence it was selected for cathodic protection in brackish mud.