ABSTRACT
Marine reinforced concrete structures are expected to suffer from chloride-induced Corrosion during their service life. The use of in-built cathodic protection system (referred as Cathodic Prevention (CPrev)) can be used to prevent corrosion by maintaining steel passivity. Such a CPrev system has been implemented on a 5.4 km long marine viaduct exposed to aggressive environment in the Indian Ocean. The tidal and submerged parts of the 48 piers were selected to receive this enhanced corrosion protection. The paper emphasizes particularly on the anode design, anode zone configuration and installation practices.
Innovative solutions with respect to the anode type and configurations were implemented to meet with the specific requirements of the viaduct construction scheme. The results of initial performance and early polarization behavior between the submerged and tidal parts are also described and discussed.
Cathodic prevention (CPrev) systems are now often specified for new reinforced concrete structures that are to be exposed to chloride containing environments.
The mechanisms and theory of cathodic prevention is comprehensively described elsewhere in the literature.1,2,3 The object of this paper is to present the field application and data for the CPrev system implemented on a 5.4 km long marine viaduct in the tropical environment at the Reunion Island off the coast of East Africa.
This paper gives account of further data and methodology most particularly with respect to field data such as anodic and steel potentials, and CP circuit resistance after concreting on-shore and after the concrete elements were placed offshore. An innovative anode system for the concrete submerged part is also presented.
In 2013, The Conseil Régional de la Réunion (The public authority of Reunion Island) let a contract for the construction of a 12.5 km long coastal road connecting the two main cities of Reunion Island, Saint-Denis and La Possession. Known as the MT3 project, part of this roadway consists of a 5.4 km long marine viaduct along the coastal perimeter of the island. Standing between 20 m and 30 m above sea level, and located 70 m away from the coast, the elevated highway serves to accommodate buses, cars, pedestrians and bicycles across a dual three-lane configuration, as shown in figures 1 and 2 below.
