Yize Zuo ^1,2 Shanchang Xu ³ Xin Fan ¹ Weiwei Liu ¹ Shuai Guan ³ Ruixin Jia ³ T. Tafsirojjaman ^4*

• ¹ China Construction First Group Constitution and Development Co. LTD., Wanghua Road 17, Beijing, 100020, China
• ² China State Construction Engineering (China), Beijing, Beijing Municipality, China
• ³ The Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education, Beijing University of Technology, 100 Pingleyuan, Beijing, China
• ⁴ School of Architecture and Civil Engineering, The University of Adelaide, Adelaide, Australia

Conventional pressure-type anchors face challenges such as difficulty in recovery, low recovery efficiency, and insufficient durability over long-term use. Although the single-use cost of Carbon Fibre Reinforced Polymer (CFRP) tendon anchors is higher than that of conventional steel tendons, recovery and reuse can significantly reduce the cost. This paper primarily investigates the bonded anchoring method of CFRP and innovatively proposes and designs a thermoplastic CFRP prestressed anchor tendon that combines both anchoring strength and recoverability. Two bonding materials, thermosetting resin and thermoplastic resin, were selected for bond strength tests. The results indicated that the bonding force of epoxy resin was 280 kN, with an anchoring efficiency of approximately 70%, making it the most suitable material among the two. However, the anchoring rate still needs improvement. Therefore, based on this, an improved design scheme was proposed, which can increase the anchoring efficiency to over 95%. The anchoring mechanism of the CFRP is based on the dispersed bonding anchor system, where a positioning plate is added at the end of the anchor cable, and epoxy resin is used for anchoring. Three anchoring performance tests were conducted on the anchor tendon based on the bonded anchoring system. The tests showed that the tensile strength of the CFRP strands ranged between 2.7-2.8 GPa, with an average anchoring efficiency of 100.5%, demonstrating excellent anchoring performance. Finally, two groups of thermoplastic recovery tests were conducted. The tests showed that when the temperature rose to 90°C, the maximum recovery force of the anchor tendon was only 17.2 kN, about 4.4% of the ultimate load. Even after the resin cooled, it could not provide more tensile strength. When the temperature rose to 150°C, the maximum recovery force of the specimen was 7.5 kN. The recovered strands were clean, with no resin residue, and both groups of recovered CFRP strands showed no damage and had an intact structure. Thus, after 10 minutes of electrical heating, a tensile force of only 4% (≤20 kN) of the ultimate load is needed to achieve the recovery and reuse of CFRP anchor tendons.