Effective Chloride Barrier for Reinforced Concrete Structures in Marine Environment

Chloride penetration into the pore space of concrete is one of the most frequent deteriorating mechanisms for reinforced concrete structures in marine environment. Once the chloride content has reached a critical value at the distance from the surface of a structural member where the steel reinforcement is placed, passivation comes to an end and corrosion may start. Service life of reinforced concrete structures can be and often is shortened considerably by chloride induced early corrosion of steel. Experiments have shown that water repellent treatment of the surface near zone by impregnation with a water repellent agent such as silane for instance or application of internal water repellent concrete may slow down chloride penetration significantly. The prediction of chloride penetration depends on many parameters and therefore is difficult. Therefore protection of concrete from chloride ingress is recommended. It will be shown that an efficient and durable chloride barrier can be built up in the surface near zone of concrete by impregnation with silane. In this way service life of reinforced concrete structures in aggressive environment can be extended considerably. By adding a water repellent agent to the fresh mix integral water repellent concrete can be produced. Chloride migration is slowed down significantly in this special type of concrete. Relevant experimental results will be presented and discussed.