Transfer of shear stresses at steel-concrete interface - Experimental tests and literature review

Shear stresses can be transferred via bond at the steel-concrete interface without having to consider any mechanical shear connectors. The research conducted shows that the use of anti-adhesive products, such as grease, reduce the bond at the steel-concrete interface in push-out tests (POTs). However, the effect is still significant, especially for fully encased steel profiles. The results of an experimental POT campaign with nine small-scale cube specimens and two composite column specimens are presented here. Three different surface conditions were examined: a) an untreated surface, b) a surface treated with anti-adhesive agent (formwork release oil) and c) a surface treated with PTFE spray. The resulting ultimate shear stresses were compared with the experimental results available in the literature [1-10]. How the different geometries of the specimens, the concrete age and the surface treatment conditions influence the bond strength are compared and summarized.