Experimental study on anchoring performance of CFRP strand in reactive powder concrete

In order to develop a bond-type anchorage for the carbon fiber reinforced polymer/plastic (CFRP) strand, the bonding behavior of CFRP strand embedded in ultra-high performance reactive powder concrete (RPC) was investigated by static test. Based on the test results, the efficient anchoring modes of CFRP strands in RPC as well as the equations to calculate the interface average bond strength and the critical anchorage length of CFRP strands under different anchoring systems were proposed. The results show that the anchoring mode of CFRP strand in anchoring section has a significant influence on its anchoring performance. The anchoring efficiency of the strand can be significantly improved by decentralizing the CFRP and using single strand to anchor separately strands within the bonding length; the twisted mode of circumjacent wire in CFRP strand is beneficial for its bonding anchorage with RPC but its tensile strength becomes lower. For the CFRP strands with a tensile strength of 2 470 MPa anchoring in the RPC with a compressive strength of 128.8 MPa, the critical anchorage lengths are 120 mm for the single centric wire, 114 mm for the single circumjacent wire, 106 mm for the decentralized CFRP strand and 231 mm for the whole anchored CFRP strand, respectively. Adding steel fibers by less than 2% of the total volume into the RPC has no obvious influence on the bonding behavior between CFRP strands and RPC.