Effect of the paste–anode interface under impressed current cathodic protection in concrete structures

Abstract

Impressed current cathodic protection (ICCP) is a powerful method to prevent and stop corrosion of steel in concrete structures. To evaluate the long‐term effect of ICCP, accelerated tests have been adopted using high current densities. A carbon fiber reinforced polymer mesh was introduced as anode. The presented research focused on the changes at the paste–anode interface as a consequence of applying current. The treated samples were characterized by various techniques. Calcium dissolution was found with an average thickness of 0.34 mm around the anode after charges of 6 × 106 C/m2 were applied, equivalent to applying 4 mA/m2 of anode surface for 30 years. Calcium dissolution resulted in a white zone around the anode, where the calcium silica ratio was lowered and almost no crystal phase was observed. NMR results show clear Q3 and Q4 peaks in the white zone, which contained extended branched and networked structures of hardened cement paste. An increased resistance caused by the formation of the white zone may eventually make the system fail because of insufficient current densities. CFRP has been proven suitable for ICCP application even at a current density of 4 A/m2 of anode surface.

Carbon enhanced cementitious coatings: Alternative anode materials for impressed current cathodic protection systems intended for reinforced concrete

“…However, by applying higher levels of the current density at varying time durations it is possible to accelerate the process and evaluate the functionality over time. [ 24 ] In Table 2 the applied current densities, the duration in terms of experimental time and the corresponding real time, and the calculated acceleration factor are presented.…”

Carbon Fibre-Reinforced Polymer (CFRP) Composites in Civil Engineering Application—A Comprehensive Review

“…CFRP is a corrosion-resistant material due to its inert properties, high strength, and resistance to harsh environments [98]. Wrapping CFRP around corroded structures can enhance their durability and lifespan, reducing the need for costly repairs and replacements [99]. Karim et al (2020) conducted a 13-week salt spray corrosion test to identify the effectiveness of various rivet Zn-Ni and Almac coating types in corrosion behaviour and the degradation of joint strength in CFRP/Aluminium joints [100].…”

Application of CFRP as anode in cathodic protection for steel reinforced concrete – a review

“…The acidification at the anode-concrete interface reduces the pH value and is also associated with calcium leaching [17], [18]. Under the effect of acidification and calcium leaching, the degraded cement pastes turns into soft grey or white silica-gel-like substance, which are amorphous and have high electrical resistivity [19].…”