Bond Strength of Geopolymer Concrete with Steel 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 understand the bonding behavior between geopolymer concrete and steel bar. 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. In this context, several authors worked also on bond strength of GPC with glass fiber-reinforced polymer (GFRP) rebars. In this paper the bond-slip behavior of GPC with both steel and GFRP reinforcement bar will be investigated. The results obtained in this work showed that GPC has a higher bond strength than the values purposed by Model Code 2010 for an OPC concrete with the same compression strength. Moreover, sand-coated GFRP bar showed a lower bonding capacity to that of deformed steel bars conventionally used for structural applications.