The carbonation and chloride penetration along highway concrete structures in a South alpine space

Abstract

Reinforced concrete structures are subjected to atmospheric agents during time. The cyclic exposure to natural parameters such as temperature, wind, rain and snowfall may emphasize the detrimental effect on structures. The different types of infrastructure may also be exposed to artificial phenomena such as, salt spreading, splashing of salt containing water or leaching effects. These phenomena contribute to the degradation of cementitious material, and the main induced mechanisms are carbonation and chloride ingress into the structures. Many types of structure such as tunnels, underpasses, walls, bridges and manholes have been investigated along a 11 km long highway close to the Alps in their South part. The aim of the study was to clarify the extent of carbonation and chloride ingress, as well as their relationship over a 40 year period. The mean climatic parameters were also registered over the years. Generally, the structures exhibited a different behaviour. The carbonation was maximal in tunnels and underpasses. A generalyl high chloride content was found for all artefacts, well beyond the 0.025 % referred to the concrete mass up to 0.400 %. The tunnels exhibited both high mean carbonation and chloride content, while all other structures indicated a slight correlation between high chloride content and low carbonation. These latter parameters were also influenced by processes such as leaching, splashing and indirect exposure to the degrading agents