Corrosion of steel in concrete: new challenges

Reinforced concrete is the most used construction material worldwide, especially for civil infrastructures, with a long and proven track record regarding structural safety and durability. This technology faces new challenges that are as follows: (1) in industrialized countries, the aging stock of assets needs high maintenance and repair with very high costs and (2) in emerging countries, a great part of the infrastructure has to be built now as well as in the future in a durable way. For both situations, this means to combine long-service life and low environmental footprint of the materials used. To reduce the environmental impact of building industry, more and more blended cements with increasingly lower clinker content will be used—with possible negative effects on the durability. Civil engineering has to move forward from an empirical-based technology to a more science-driven way that allows understanding deterioration mechanisms and service life prediction. This article briefly presents the fundamentals of durability of RC structures. Focusing on the challenges “new blended cements,” it is shown how the use of new sensors and measuring setups can contribute to the understanding of the carbonation mechanism and the corrosion rate of steel in carbonated concrete. Finally, some new aspects to the everlasting research challenge “critical chloride content” both from experimental and theoretical side are presented.