The steel–concrete interface

TLDR

The steel–concrete interface (SCI) is widely recognized to influence reinforced concrete durability, yet a systematic overview and detailed documentation of its various aspects remain lacking. The paper compiles a comprehensive list of local characteristics at the SCI, reviews their properties and occurrences in both engineering structures and laboratory specimens, proposes a systematic descriptive framework, and recommends further research. The authors compiled a comprehensive list of possible local characteristics at the steel–concrete interface and reviewed their properties and occurrences in both engineering structures and laboratory specimens. The steel–concrete interface shows marked spatial inhomogeneity and varies widely between structures and members, especially between pre‑ and post‑1970/1980s designs, with laboratory specimens differing from real structures, indicating that laboratory findings must be applied to engineering structures with caution.

Abstract

Although the steel–concrete interface (SCI) is widely recognized to influence the durability of reinforced concrete, a systematic overview and detailed documentation of the various aspects of the SCI are lacking. In this paper, we compiled a comprehensive list of possible local characteristics at the SCI and reviewed available information regarding their properties as well as their occurrence in engineering structures and in the laboratory. Given the complexity of the SCI, we suggested a systematic approach to describe it in terms of local characteristics and their physical and chemical properties. It was found that the SCI exhibits significant spatial inhomogeneity along and around as well as perpendicular to the reinforcing steel. The SCI can differ strongly between different engineering structures and also between different members within a structure; particular differences are expected between structures built before and after the 1970/1980s. A single SCI representing all on-site conditions does not exist. Additionally, SCIs in common laboratory-made specimens exhibit significant differences compared to engineering structures. Thus, results from laboratory studies and from practical experience should be applied to engineering structures with caution. Finally, recommendations for further research are made.