Service Life of Reinforced Concrete Infrastructure in Marine Environments

Abstract

Reinforced Concrete (RC) is one of the most widely used man-made building materials, even in aggressive conditions. The marine environment is one such place with aggressive conditions, where reinforced concrete is widely used.

The Service Life of a structure can be described as the amount of time for which the structure can carry the service loads imposed upon it without failure. Service life of RC infrastructure is determined by whichever environmental or loading effect most significantly contributes to the structural failure of RC. In marine areas, this effect is deterioration due to reinforcement corrosion, caused by chloride ingress.

Chloride-induced corrosion has many causes, including concrete mix design, construction quality, initial concrete condition, and the surrounding environment.

RC structures constructed from non-reactive dolomite aggregates have enhanced durability against corrosion. Cracks occur in most RC structures at the start of its service life. These cracks readily allow chloride ingress and thus reduce the service life of the RC. The exposure conditions and environment affect the aggressiveness of chloride-induced corrosion in an RC structure determine. These effects have complex causes and interactions and should be considered holistically.

In marine environments an integral part of increasing service life involves preventing and mitigating the adverse effects of chloride-induced corrosion. Ways in which this can be achieved include: including mineral admixtures in concrete mix, using protective coatings on concrete surfaces, monitoring the condition of RC elements, suitable concrete design and adequate construction quality.

Mineral admixtures are used to improve the durability of RC by chemically and physically improving concrete properties. Surface coatings are used on new and repaired RC surfaces in order to preserve initial alkaline environment of the concrete, stop electrolytic processes, and create a surface barrier to control the ingress of aggressive substances. Sensors and models are often used as part of an on-going monitoring system. This helps to ensure cost-effective maintenance and repair. A systematic quality control program ensures concrete reaches the required strengths while proactively managing corrosion risks due to poor construction quality.

It can be seen that a holistic view of the considerations (and mitigation measures) related to chloride-induced corrosion is important in order to ensure an acceptable service life at the design and maintenance stages.

Keywords: Concrete, Marin infrastructure