Covercrete with hybrid functions – A novel approach to durable reinforced concrete structures

Artikel i vetenskaplig tidskrift, 2012

Due to the corrosion of steel in reinforced concrete structures, the concrete with low water-cement ratio (w/c), high cement content and large cover thickness is conventionally used for prolonging the passivation period of steel. Obviously, this conventional approach to durable concrete structures is at the sacrifice of more CO2 emission and natural resources through consuming higher amount of cement and more constituent materials, which is against sustainability. By placing an economically affordable conductive mesh made of carbon fibre or conductive polymer fibre in the near surface zone of concrete acting as anode we can build up a cathodic prevention system with intermittent low current density supplied by e.g. the solar cells. In such a way, the aggressive negative ions such as chloride, carbonate and sulphate can be stopped near the cathodic (steel) zone. Thus the reinforcement steel is prevented from corrosion even in the concrete with relatively high w/c and small cover thickness. This conductive mesh functions not only as electrode, but also as surface reinforcement to prevent concrete surface from cracking. Therefore, this new type of covercrete has hybrid functions. This paper presents the theoretical analysis of feasibility of this approach and discusses the potential durability problems and possible solutions to the potential problems.