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

Abstract

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 fiber or conductive polymer fiber 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 Cl−, ${\rm CO}_{3}^{2- } $, and ${\rm SO}_{4}^{2- } $ 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.

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

“…[34] The acidification has a direct effect on the structure since it consumes calcium hydroxide (CaOH, Portlandite), where an increase in acidity eventually destroys the calcium-silicate-hydrate (CSH) gel by calcium leaching and deteriorates the bond strength between the cementitious substrate and the anode. [35] In accordance with this, the results strongly suggest that the porous zone indicated by the dashed circle in Figure 13a is due to such microstructural changes and also the most likely reason for the increased electrical resistance of the system.…”

Durability behavior of polymer impregnated carbon textiles in alkaline solution as CP anode

“…In the Pourbaix diagrams, the pH value at the contact surface between solution and carbon is considered as influencing factor of the carbon's stability. However, it does not take the process of acidification at the anode's surface into account, which is a general and commonly reported issue leading to locally strongly acidic conditions.…”

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

“…Studies have also been made to combine the reinforcing property together with the anode function [25], [26]. Zhu et al [27] reported stable anode performance in accelerated ICCP tests of CFRP strip in simulated pore solutions.…”