Decreased useful life in air chamber reinforced concrete elements under sanitary floors by carbonation corrosion

Abstract

Reinforced concrete elements located in enclosed spaces with medium to high humidity, inside air chambers beneath sanitary floors, are shielded from rainfall. However, the longevity of these elements, as estimated by durability models for predicting the corrosion of their reinforcement due to carbonation, significantly exceeds the actual service lives observed. The discrepancy between estimated and actual service lives often results in structural failures of sanitary floors, which may collapse without warning, given the inherent challenges associated with inspection and maintenance. This study thoroughly examined the condition of reinforced concrete elements beneath sanitary floors in four educational institutes located in the Valencian Community, where corrosion of reinforcement due to carbonation was present. The study entailed an analysis of the relative humidity, temperature, and presence of CO2 within these enclosed spaces, in comparison to exterior areas or other parts of the building. Furthermore, tests were conducted to assess the characteristic strength of the concrete and the depth of carbonation. Additionally, the surface area of the chamber used for ventilation was assessed in light of the minimum requirements. Notwithstanding, the concrete cover of the beams and columns exhibited carbonation, with the reinforcement's corrosion in a propagation period. The study's findings revealed that the service life of the structural elements is substantially shorter than initially anticipated, in part due to advanced carbonation processes that are attributable to the harsh environment in which they are located.