Self-consolidating concrete and its bond to reinforcement

Research has shown that high slump concrete mixtures can exhibit bond problems especially at the top-cast bars due to blocking of bleed water underneath the reinforcement. As far as self-consolidating concrete is concerned there are many conflicting results in the literature regarding its bond to reinforcement. The scope of this paper is to present an experimental methodology on assessing the quality of the interface between concrete and steel bars. Four different self-consolidating concrete and conventional vibrated concrete mixtures, with diverse rheological characteristics, are examined. The quality of the interface is assessed by image analysis of cut sections containing reinforcement bars at different cast-heights. The experimental investigation revealed the formation of significant caving under the top-cast bars, which can affect considerably the bond strength.