Bond of FRP Rebars in Fine-Grained Alkali Activated Concrete

Alkali activated cement (AAC) is an alternative binder with a promising potential to replace ordinary Portland cement (OPC) for solving the environmental issue the latter is facing. The use of fibre reinforced polymer (FRP) reinforcements with AAC concrete make it possible to have a corrosion resistant environmentally friendly reinforced concrete structure. Bond behaviour is critical in reinforced concrete structure, hence have to be studied for such new alternative materials. In this study, different FRP rebars with varying fibres and surface profiles are tested using pullout tests to understand their bond behaviour. Three different fine-grained AAC concretes with a maximum aggregate size of 3.15 mm and FRP bars with braided, milled and smooth surfaces were used. The concrete's compressive strength showed a significant influence on the bond strength. Milled carbon and glass FRP bars did not show a significant difference in bond strength. For a compressive strength of 65 MPa an average bond strength of about 18 MPa was observed in both cases. The carbon bars with no surface preparation (smooth bars) resulted in a much lower bond strength (4 MPa) than the milled and braided bars.