Bond-slip Behavior Between Geopolymer Concrete and Deformed Steel Bar

Presented by Maria Antonietta Aiello, University of Salento Geopolymer concrete elements analyzed in previous research showed high mechanical performances, even better than ordinary Portland Cement (OPC) concrete. This led several researchers to consider this material in reinforced structural elements. In the last decades both direct pull‐out and beam‐end tests were carried out with geopolymer concrete and deformed steel bar aiming to understand the bond‐slip behavior between geopolymer concrete and steel bar. Generally, it has been observed that the maximum bond strength with deformed steel bar was higher for geopolymer concrete (GPC) than OPC concrete. This improvement in bond‐slip behavior is mainly due to the dense and compact microstructure of GPC: it enhances the compression strength of concrete and avoid defect formations near the reinforcing bar; this implies that theexisting design equation for bond strength prediction of ordinary concrete can be conservatively used also for GPC. In this study, the bond‐slip behavior between GPC and steel reinforcement bars will be investigated by performing pull‐out test in order to define a new more suitable bond stress law. In particular, two different factors affecting bond strength will be focused, namely the bar diameter and the chemical composition of geopolymer.