Title: Bond Properties of High-Strength Carbon Fiber-Reinforced Polymer Strands

Author(s): Weichen Xue, Xiaohui Wang, and Shulu Zhang

Publication: Materials Journal

Volume: 105

Issue: 1

Appears on pages(s): 11-19

Keywords: bond; carbon fiber-reinforced polymer; pullout test; strand; strength

DOI: 10.14359/19202

Date: 2/1/2008

Abstract:
Forty-eight pullout tests were conducted to examine the bond properties of high-strength carbon fiber-reinforced polymer (CFRP) strands in different bonding agents, including normal concrete, high-performance concrete, epoxy resin, and grout. The bond properties were examined through measurements of slippages and corresponding bond stresses for CFRP strands as well as steel strands for comparison purposes. Studies show that bond stresses reach a maximum when the slippages of high-strength CFRP strands range from 0.012 to 0.016 in. (0.3 to 0.4 mm), and for steel strands, the slippages are approximately 0.787 in. (20 mm). Bar diameters 0.492 to 0.598 in. (12.5 to 15.2 mm) of CFRP strands have a moderate influence on allowable bond strength. The higher concrete compressive strength develops higher bond strength. The allowable bond strength (determined at 0.03937 in. [1.0 mm] slippage) of CFRP strands is 1.3 to 1.4 times that of steel strands, whereas the maximum bond stresses of steel strands are 30 to 50% higher than that of CFRP strands. Although the maximum bond stresses in steel strands are higher than those in CFRP strands, they occur at large slips, which explains why the allowable bond stresses are lower. In addition, on the basis of experimental tests, bond stress versus slip models for high-strength CFRP strands and steel strands are proposed.