Bond Behavior of Geopolymer Concrete with CFRP and GFRP Bars

The high mechanical performances showed by geopolymer concrete led several researchers to investigate about possibilities of using this material in reinforced structural elements. Since geopolymer binder has a different microstructure from ordinary Portland Cement (OPC) it is necessary to investigate on its bonding behavior with steel bar that as well-known influences the service and ultimate conditions. For this reason, in the last decades both direct pull-out and beam-end tests were carried out with this material. Generally, it has been observed that geopolymer concrete (GPC) has higher bond strength than OPC due to the higher compression strength and the dense and compact microstructure of GPC. This means that the existing design equation for bond strength prediction of ordinary concrete can be conservatively used also for GPC. In this paper the mechanical properties of GPC will be analyzed and the bond-slip behavior of GPC and both CFRP and GFRP bars has been studied. The experimental data are analyzed and discussed in terms of bond stress transfer mechanisms and mode of failure.