Experimental Characterization of Bond-Slip Behavior of Carbon Fiber-Reinforced Polymer (CFRP) Strip Embedded in High-Strength Strain-Hardening Cementitious Composites (SHCC) Under Direct Tension

Abstract

<p>Strain-hardening Cementitious Composites (SHCC) exhibit unique tensile strain-hardening behavior accompanied by closely spaced cracks. Recent research has shown that incorporating Carbon Fiber-Reinforced Polymer (CFRP) laminate strips together with SHCC in the tensile zone can effectively enhance/recover the load-bearing capacity of RC beams. Additionally, the widely-adopted Near Surface Mounted (NSM) technique has proven effective in retrofitting and rehabilitating underperforming RC structures. The bond behavior between concrete and the NSM-CFRP system has been extensively evaluated, but information on the bond behavior between SHCC and NSM-CFRP is very limited. This study aims to investigate the bond behavior between SHCC and NSM-CFRP laminate strips under direct tension, which is crucial for optimizing the design and applications of this system in practical scenarios. High-strength SHCC with a compressive strength of 112 MPa, tensile strength of 8.6 MPa, and tensile strain capacity of 5.5% was used. The effects of different sand coatings, number of CFRP layers, cover thickness, and bond lengths were discussed. The findings show that the bond behavior between SHCC and CFRP can be improved by utilizing proper sand size. Additionally, the effective bond strength decreases with increasing bond length, but increases with increasing strip width and strip layers. The findings of this study can contribute to developing innovative and reliable techniques for reinforcing and rehabilitating RC structures.</p>