Low carbonation of concrete found on 100-year-old bridges

This work investigates an unexpectedly low carbonation depth found in two bridges. A protection against carbonation is ensured by approximately 2-3 mm thick dense plaster coat covering the outer surface of concrete. The plaster coat consists prevailingly of compact carbonate micro particles, showing no open pores and such a density, which gives this extremely thin layer non-permeability property for carbon oxide penetration over time.