In recent years, an interest in the corrosion monitoring technique of steel in marine concrete structures has been increased. Monitoring the reinforcement corrosion, it is crucial to be aware of corrosion threshold for damages or early repair and rehabilitation due to economical and safety aspects. A number of corrosion monitoring sensors have been proposed world-widely to predict the proper repair time of concrete structures. However, most of sensors introduced so far have some limitations to reach to the reliable status to evaluate corrosion continuously and accurately. A multifunctional compact sensor to monitor several corrosion factors has been proposed in this study, and the electrochemical and physical evaluation has been carried out to investigate rebar potential, corrosion rate, passivation state of rebar surface, and temperature of concrete. Five different environments, i.e. atmospheric, tap water, seawater, 15% seawater, and 15% seawater wet-dry cycle, have been applied, and a reasonable prediction of corrosion has been obtained in terms of nondestructive electrochemical point of view.

This paper represents the behaviors of hybrid cathodic protection (hybrid CP) system in a reinforced concrete column specimen. Cathodic protection (CP) is widely used as a means of protecting corrosion for marine concrete structures such as harbor and offshore facilities. Specifically, hybrid CP, which is the combination both sacrificial anode cathodic protection (SACP) system and impressed current cathodic protection (ICCP) system, can be an optimum way to protect corrosion. Some complex concrete structures as well as harbor constructions are considered to be protected by both systems. Especially, it becomes more complicated to protect corrosion damage of concrete structures in the tidal and splash zones of marine environment. In case of Yellow Sea of the South Korea, the tidal zone reaches to 6~8m. On the condition that this system is well applied in the Yellow Sea, it is expected to show a good CP behavior to solve an underprotection problem, especially in tidal and splash zones. In this study, the hybrid system installed both the ICCP with Timesh anode and the SACP with zinc anode has been adopted to verify the current influence through laboratory experiment. CP potential and current have been investigated, in addition, 4-hour depolarization test has been involved to reveal the effectiveness of hybrid CP.

This experimental study proposes a conductive mortar to increase the efficiency of the sacrificial anode cathodic protection (SACP) system by decreasing resistivity and maintaining it for a long time. The resistivity characteristics of the mortar that contained electrically conductive admixtures and/or chemical agents were evaluated by the Brunauer–Emmett–Teller (BET) method and resistivity measurements. The conductive mortar with activated carbon and sodium hydroxide had the lowest resistivity. The SACP system was then designed to evaluate the cathodic protection (CP) performance with the proposed activated-carbon-based conductive mortar. The proposed conductive mortar contributed to lower CP potential and higher current density and depolarization potential than the general mortar.

No abstract

No abstract