Experimental study on bond properties between GFRP bars and self-compacting concrete

In order to investigate the bond properties between glass fiber reinforced polymer (GFRP) bars and selfcompacting concrete (SCC), pull-out tests on 66 GFRP reinforced SCC specimens were designed and carried out. The effects of SCC cover thickness, bond length, and diameter of GFRP bars, as well as the types of fibers added to SCC on the bond properties were investigated. In addition, the failure modes of specimens were analyzed and the bond-slip curve was fitted as well. The conclusion can be described as follows: (1) There are three primary forms of bond failure of specimens: splitting failure, pull-out failure, and pull-out failure with cracks. (2) The bond strength of GFRP bar reinforced SCC specimens can be improved by appropriately increasing the SCC cover thickness and adding fibers to SCC, but it could rapidly decrease with the increasment of GFRP bar diameter and bond length. (3) The CMR model fits well to test data of GFRP/SCC specimens with a larger cover thickness or adding fibers. In comparison, the mBPE model fits well to those with a large diameter or bond length of GFRP bars. The critical bond length of GFRP bars and the recommended thickness of the SCC cover are proposed based on both theoretical and experimental investigations.